Resist composition and method of forming resist pattern

ABSTRACT

A resist composition including a compound (D0) formed of an anion moiety and a cation moiety which is represented by Formula (d0), and a resin component (A1) which has a constitutional unit (a0) obtained from a compound represented by Formula (a0-1), in which a polymerizable group at a W portion is converted into a main chain, and a constitutional unit (a1) containing an acid decomposable group whose polarity is increased due to an action of an acid. In Formula (d0), Rd0 represents a substituent and n represents an integer of 2 or greater. In Formula (a0-1), Wax0 represents an (nax0+1)-valent aromatic hydrocarbon group which may have a substituent.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a resist composition and a method offorming a resist pattern using the resist composition.

Priority is claimed on Japanese Patent Application No. 2018-228560,filed on Dec. 5, 2018, the content of which is incorporated herein byreference.

Description of Related Art

In lithography techniques, for example, a resist film formed of a resistmaterial is formed on a substrate, and the resist film is subjected toselective exposure, followed by a developing treatment, thereby forminga resist pattern having a predetermined shape on the resist film. Aresist material in which the exposed portions of the resist film becomesoluble in a developing solution is called a positive type, and a resistmaterial in which the exposed portions of the resist film becomeinsoluble in a developing solution is called a negative type.

In recent years, in the production of semiconductor elements and liquidcrystal display elements, advances in lithography techniques have led torapid progress in the field of pattern miniaturization. Typically, theseminiaturization techniques involve shortening the wavelength (increasingthe energy) of the exposure light source. Specifically, ultravioletradiation typified by g-line and i-line radiation has been used in therelated art, but nowadays KrF excimer lasers and ArF excimer lasers areused in mass production. Furthermore, research is also being conductedinto lithography techniques that use an exposure light source having awavelength shorter (energy higher) than these excimer lasers, such aselectron beams (EB), extreme ultraviolet rays (EUV), and X rays.

Resist materials for use with these types of exposure light sourcesrequire lithography characteristics such as a high resolution capable ofreproducing patterns of minute dimensions, and a high level ofsensitivity to these types of exposure light sources.

As a resist material that satisfies these requirements, in the relatedart, a chemically amplified resist composition which includes a basematerial component whose solubility in a developing solution is changeddue to an action of an acid and an acid-generator component thatgenerates an acid upon exposure has been used.

For example, in a case where the developing solution is an alkalideveloping solution (alkali developing process), as a positive typechemically amplified resist composition, a composition which contains aresin component (base resin) whose solubility in an alkali developingsolution is increased due to an action of an acid and an acid generatorcomponent has been typically used. In a case where a resist film formedusing such a resist composition is selectively exposed at the time offorming a resist pattern, in exposed portions, an acid is generated fromthe acid generator component, and the polarity of the base resinincreases by the action of the generated acid, thereby making theexposed portions of the resist film soluble in the alkali developingsolution. Thus, by conducting alkali development, and the unexposedportions of the resist film remain to form a positive type resistpattern.

On the other hand, in a case where such a chemically amplified resistcomposition is applied to a solvent developing process using adeveloping solution containing an organic solvent (organic developingsolution), since the solubility in an organic developing solution isrelatively decreased at the time of an increase in polarity of the baseresin, the unexposed portions of the resist film are dissolved andremoved by the organic developing solution, and a negative type resistpattern in which the exposed portions of the resist film are remainingis formed. Such a solvent developing process for forming a negative typeresist pattern is also referred to as a “negative type developingprocess”.

In formation of a resist pattern, the behavior of an acid generated froman acid generator component upon exposure is regarded as a factor thatgreatly affects the lithography characteristics.

Meanwhile, a chemically amplified resist composition which contains anacid generator component as well as an acid diffusion control agent thatcontrols diffusion of an acid generated from the acid generatorcomponent upon exposure has been suggested.

For example, Japanese Unexamined Patent Application, First PublicationNo. 2014-115386 discloses a resist composition containing a resincomponent whose solubility in a developing solution is changed due to anaction of an acid; an acid generator component; and a photoreactivequencher which has a cation moiety having a specific structure as anacid diffusion control agent. This photoreactive quencher is consideredas a component that exhibits a quenching effect by causing an ionexchange reaction with an acid generated from an acid generatorcomponent. Further, due to the blending with such a photoreactivequencher, diffusion of the acid generated from the acid generatorcomponent in unexposed portions from exposed portions of the resist filmis controlled so that the lithography characteristics are improved.

SUMMARY OF THE INVENTION

Recently, with progression of advancement in lithography technology andexpansion of application fields, pattern miniaturization is rapidlyprogressing. With this trend, a technique which enables formation of afine pattern, in which the dimension of the pattern width is less than100 nm, with an excellent shape is required at the time of manufacturinga semiconductor element and the like.

However, in a case where a fine pattern (for example, a fine line andspace pattern) is intended to be formed on a substrate using a resistcomposition of the related art, a problem of the resolution such asoccurrence of pattern collapse is generated. Further, even in a casewhere the resolution can be improved, it is insufficient to satisfy therequirement, for example, in terms of the uniformity (reduction inroughness) of the space width in the pattern. Further, in a case wherethe sensitivity of an exposure light source such as EUV is intended toincrease, there is a problem in that the uniformity (reduction inroughness) of the space width is unlikely to be obtained.

The present invention has been made in consideration of theabove-described circumstances, and an object thereof is to provide aresist composition which has excellent sensitivity, reduced roughness,and excellent resolution, and a method of forming a resist pattern.

In order to achieve the above-described object, the present inventionemploys the following configuration.

According to a first aspect of the present invention, there is provideda resist composition which generates an acid upon exposure and whosesolubility in a developing solution is changed due to an action of theacid, the resist composition including: a resin component (A1) whosesolubility in a developing solution is changed due to the action of anacid; and a compound (D0) formed of an anion moiety and a cation moietywhich is represented by Formula (d0), in which the resin component (A1)has a constitutional unit (a0) obtained from a compound represented byFormula (a0-1), in which a polymerizable group at a W portion isconverted into a main chain, and a constitutional unit (a1) containingan acid decomposable group whose polarity is increased due to the actionof the acid.

[In the formula, M^(m+) represents an m-valent organic cation, R^(d0)represents a substituent, p represents an integer of 0 to 3, and in acase where p represents 2 or 3, a plurality of substituents as R^(d0)may be the same as or different from one another, q represents aninteger of 0 to 3, n represents an integer of 2 or greater, where arelationship of “n+p≤(q×2)+5” is satisfied.]

[In the formula, W represents a polymerizable group-containing group,Wa^(x0) represents an (n_(ax0)+1)-valent aromatic hydrocarbon groupwhich may have a substituent, and n_(ax0) represents an integer of 1 to3.]

According to a second aspect of the present invention, there is provideda method of forming a resist pattern, including: a step of forming aresist film on a support using the resist composition according to thefirst aspect; a step of exposing the resist film; and a step ofdeveloping the exposed resist film to form a resist pattern.

According to the resist composition of the present invention, it ispossible to form a resist pattern which has excellent sensitivity,reduced roughness, and excellent resolution at the time of forming aresist pattern.

DETAILED DESCRIPTION OF THE INVENTION

In the present description and claims, the term “aliphatic” is arelative concept used in relation to the term “aromatic”, and defines agroup or compound that has no aromaticity.

The term “alkyl group” includes linear, branched or cyclic, monovalentsaturated hydrocarbon, unless otherwise specified. The same applies forthe alkyl group in an alkoxy group.

The term “alkylene group” includes linear, branched or cyclic, divalentsaturated hydrocarbon, unless otherwise specified.

A “halogenated alkyl group” is a group in which some or all hydrogenatoms of an alkyl group is substituted with halogen atoms. Examples ofthe halogen atom include a fluorine atom, a chlorine atom, a bromineatom and an iodine atom.

A “fluorinated alkyl group” or a “fluorinated alkylene group” is a groupin which some or all hydrogen atoms of an alkyl group or an alkylenegroup have been substituted with fluorine atoms.

The term “constitutional unit” indicates a monomer unit that contributesto the formation of a polymer compound (a resin, a polymer, or acopolymer).

The expression “may have a substituent” means that a case where ahydrogen atom (—H) is substituted with a monovalent group, or a casewhere a methylene (—CH₂—) group is substituted with a divalent group.

The term “exposure” is used as a general concept that includesirradiation with any form of radiation.

A “constitutional unit derived from acrylic acid ester” indicates aconstitutional unit that is formed by the cleavage of the ethylenicdouble bond of acrylic acid ester.

The “acrylic acid ester” indicates a compound in which the terminalhydrogen atom of the carboxy group of acrylic acid (CH₂═CH—COOH) hasbeen substituted with an organic group.

In the acrylic acid ester, the hydrogen atom bonded to the carbon atomat the α-position may be substituted with a substituent. The substituent(R^(α0)) that substitutes the hydrogen atom bonded to the carbon atom atthe α-position is an atom other than a hydrogen atom or a group, andexamples thereof include an alkyl group having 1 to 5 carbon atoms and ahalogenated alkyl group having 1 to 5 carbon atoms. Further, itaconicacid diester in which the substituent (R^(α0)) is substituted with asubstituent having an ester bond or α-hydroxyacryl ester in which thesubstituent (R^(α0)) is substituted with a hydroxyalkyl group or a groupobtained by modifying a hydroxyl group thereof can be exemplified asacrylic acid ester. A carbon atom at the α-position of acrylic acidester indicates the carbon atom bonded to the carbonyl group of acrylicacid, unless otherwise specified.

Hereinafter, acrylic acid ester in which the hydrogen atom bonded to thecarbon atom at the α-position is substituted with a substituent is alsoreferred to as α-substituted acrylic acid ester”. Further, acrylic acidester and α-substituted acrylic acid ester are also collectivelyreferred to as “(α-substituted) acrylic acid ester”.

A “constitutional unit derived from acrylamide” indicates aconstitutional unit that is formed by the cleavage of the ethylenicdouble bond of acrylamide.

The acrylamide may have the hydrogen atom bonded to the carbon atom atthe α-position substituted with a substituent, and may have either orboth terminal hydrogen atoms on the amino group of acrylamidesubstituted with a substituent. A carbon atom at the α-position ofacrylamide indicates the carbon atom bonded to the carbonyl group ofacrylamide, unless otherwise specified.

As the substituent which substitutes the hydrogen atom bonded to thecarbon atom at the α-position of acrylamide, the same substituents asthose described above for the substituent (R^(α0)) at the α-position ofthe above-described α-position of the α-substituted acrylic acid estercan be exemplified.

A “constitutional unit derived from hydroxystyrene” indicates aconstitutional unit that is formed by the cleavage of an ethylenicdouble bond of hydroxystyrene. A “constitutional unit derived from ahydroxystyrene derivative” indicates a constitutional unit formed by thecleavage of an ethylenic double bond of a hydroxystyrene derivative.

The term “hydroxystyrene derivative” includes compounds in which thehydrogen atom at the α-position of hydroxystyrene has been substitutedwith another substituent such as an alkyl group or a halogenated alkylgroup; and derivatives thereof. Examples of the derivatives thereofinclude hydroxystyrene in which the hydrogen atom of the hydroxyl grouphas been substituted with an organic group and may have the hydrogenatom at the α-position substituted with a substituent; andhydroxystyrene which has a substituent other than a hydroxyl groupbonded to the benzene ring and may have the hydrogen atom at theα-position substituted with a substituent. Further, the α-position(carbon atom at the α-position) indicates the carbon atom having thebenzene ring bonded thereto, unless otherwise specified.

As the substituent which substitutes the hydrogen atom at the α-positionof hydroxystyrene, the same substituents as those described above forthe substituent at the α-position of the above-described α-substitutedacrylic acid ester can be exemplified.

A “constitutional unit derived from vinylbenzoic acid or a vinylbenzoicacid derivative” indicates a constitutional unit that is formed by thecleavage of the ethylenic double bond of vinylbenzoic acid or avinylbenzoic acid derivative.

The term “vinylbenzoic acid derivative” includes compounds in which thehydrogen atom at the α-position of vinylbenzoic acid has beensubstituted with another substituent such as an alkyl group or ahalogenated alkyl group; and derivatives thereof.

Examples of the derivatives thereof include vinylbenzoic acid in whichthe hydrogen atom of the carboxy group has been substituted with anorganic group and may have the hydrogen atom at the α-positionsubstituted with a substituent; and vinylbenzoic acid which has asubstituent other than a hydroxyl group and a carboxy group bonded tothe benzene ring and may have the hydrogen atom at the α-positionsubstituted with a substituent. Further, the α-position (carbon atom atthe α-position) indicates the carbon atom having the benzene ring bondedthereto, unless otherwise specified.

The term “styrene derivative” is a concept including those obtained bysubstitution of a hydrogen atom at the α-position of styrene with othersubstituents such as an alkyl group and a halogenated alkyl group; andthese derivatives. Examples of these derivatives include those obtainedby bonding a substituent to a benzene ring of hydroxystyrene in which ahydrogen atom at the α-position may be substituted with a substituent.Further, the α-position (carbon atom at the α-position) indicates thecarbon atom having the benzene ring bonded thereto, unless otherwisespecified.

The term “constitutional unit derived from styrene” or “constitutionalunit derived from a styrene derivative” indicates a constitutional unitformed by cleavage of an ethylenic double bond of styrene or a styrenederivative.

As the alkyl group as a substituent at the α-position, a linear orbranched alkyl group is preferable, and specific examples include alkylgroups of 1 to 5 carbon atoms, such as a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group, and a neopentylgroup.

Specific examples of the halogenated alkyl group as the substituent atthe α-position include groups in which some or all hydrogen atoms of theabove-described “alkyl group as the substituent at the α-position” aresubstituted with halogen atoms. Examples of the halogen atom include afluorine atom, a chlorine atom, a bromine atom and an iodine atom, and afluorine atom is particularly preferable.

Specific examples of the hydroxyalkyl group as the substituent at theα-position include groups in which some or all hydrogen atoms of theabove-described “alkyl group as the substituent at the α-position” aresubstituted with a hydroxyl group. The number of hydroxyl groups in thehydroxyalkyl group is preferably 1 to 5, and most preferably 1.

In the present specification and the scope of the present patent claims,asymmetric carbons may be present or enantiomers or diastereomers may bepresent depending on the structures of the chemical formulae. In thiscase, these isomers are represented by one chemical formula. Theseisomers may be used alone or in the form of a mixture.

(Resist Composition)

The resist composition according to the first aspect of the presentinvention is a resist composition which generates an acid upon exposureand whose solubility in a developing solution is changed due to anaction of the acid. The resist composition includes a resin component(A) (hereinafter, also referred to as a “component (A)”) whosesolubility in a developing solution is changed due to the action of anacid, and a compound (D0) (hereinafter, also referred to as a “component(D0)”) formed of an anion moiety and a cation moiety which isrepresented by Formula (d0). The component (A) has a resin component(A1) (hereinafter, also referred to as a “component (A1)” having aconstitutional unit (a0) obtained from a compound represented by Formula(a0-1), in which a polymerizable group at a W portion is converted intoa main chain, and a constitutional unit (a1) containing an aciddecomposable group whose polarity is increased due to the action of theacid.

As an embodiment of such a resist composition, a resist compositionwhich contains the component (A) and the component (D0) as a basecomponent (hereinafter, also referred to as a “component (D)”) thattraps an acid generated upon exposure (that is, controls diffusion of anacid) is exemplified. A resist composition which contains an acidgenerator component (B) (hereinafter, also referred to as a “component(B)”) that generates an acid upon exposure in addition to the component(A) and the component (D0) is preferably exemplified.

In a case where a resist film is formed using the resist compositionaccording to the present embodiment and the formed resist film issubjected to a selective exposure, an acid is generated from thecomponent (B) at exposed portions of the resist film, and the generatedacid acts on the component (A) to change the solubility of the component(A) in a developing solution, whereas the solubility of the component(A) in a developing solution is not changed at unexposed portions of theresist film, thereby generating difference in solubility in a developingsolution between exposed portions and unexposed portions. Therefore, bysubjecting the resist film to development, the exposed portions of theresist film are dissolved and removed to form a positive type resistpattern in a case where the resist composition is of a positive type,whereas the unexposed portions of the resist film are dissolved andremoved to form a negative type resist pattern in a case where theresist composition is of a negative type.

In the present specification, a resist composition which forms apositive type resist pattern by dissolving and removing the exposedportions of the resist film is called a positive type resistcomposition, and a resist composition which forms a negative type resistpattern by dissolving and removing the unexposed portions of the resistfilm is called a negative type resist composition.

The resist composition of the present embodiment may be a positive typeresist composition or a negative type resist composition. Further, inthe formation of a resist pattern, the resist composition of the presentembodiment can be applied to an alkali developing process using analkali developing solution in the developing treatment, or a solventdeveloping process using a developing solution containing an organicsolvent (organic developing solution) in the developing treatment.

The resist composition of the present embodiment has a function ofgenerating an acid upon exposure, and the component (A) together withthe component (B) may generate an acid upon exposure.

In a case where the component (A) generates an acid upon exposure, thecomponent (A) becomes a “base material component which generates an acidupon exposure and whose solubility in a developing solution is changeddue to the action of the acid”.

In a case where the component (A) is a base material component whichgenerates an acid upon exposure and whose solubility in a developingsolution is changed due to the action of the acid, it is preferable thata component (A1) described below is a polymer compound which generatesan acid upon exposure and whose solubility in a developing solution ischanged due to the action of the acid. As such a polymer compound, aresin having a constitutional unit that generates an acid upon exposureis exemplified. A known monomer can be used as the monomer that derivesthe constitutional unit generating an acid upon exposure.

<Component (A)>

In the resist composition of the present embodiment, the component (A)is a base material component whose solubility in a developing solutionis changed due to the action of an acid and which contains the component(A1). In the alkali developing process and the solvent developingprocess, since the polarity of the base material component before andafter the exposure is changed by using the component (A1), an excellentdevelopment contrast between exposed portions and unexposed portions canbe obtained.

In a case of applying an alkali developing process, the base materialcomponent having the component (A1) is substantially insoluble in analkali developing solution prior to exposure, but in a case where acidis generated from the component (B) upon exposure, the action of thisacid causes an increase in the polarity of the base material component,thereby increasing the solubility of the component (A1) in an alkalideveloping solution. Therefore, in the formation of a resist pattern, byconducting selective exposure of a resist film formed by applying theresist composition to a support, the exposed portions of the resist filmchange from an insoluble state to a soluble state in an alkalideveloping solution, whereas the unexposed portions of the resist filmremain insoluble in an alkali developing solution, and hence, a positivetype resist pattern is formed by alkali developing.

Meanwhile, in a case of a solvent developing process, the base materialcomponent having the component (A1) exhibits high solubility in anorganic developing solution prior to exposure, and in a case where acidis generated from the component (B) upon exposure, the polarity of thecomponent (A1) is increased by the action of the generated acid, therebydecreasing the solubility of the component (A1) in an organic developingsolution. Therefore, in the formation of a resist pattern, by conductingselective exposure of a resist film formed by applying the resistcomposition to a support, the exposed portions of the resist filmchanges from an soluble state to an insoluble state in an organicdeveloping solution, whereas the unexposed portions of the resist filmremain soluble in an organic developing solution. As a result, byconducting development using an organic developing solution, a contrastbetween the exposed portions and the unexposed portions can be made, anda negative type resist pattern can be formed.

In the resist composition according to the present embodiment, thecomponent (A) may be used alone or in combination of two or more kindsthereof.

In Regard to Component (A1)

The resin component (A1) is a base material component having aconstitutional unit (a0) in which a polymerizable group at a W portionis converted into a main chain and a constitutional unit (a1) containingan acid decomposable group whose polarity is increased due to the actionof the acid in a compound represented by Formula (a0-1).

Further, the component (A1) may have other constitutional units asnecessary in addition to the constitutional unit (a0) and theconstitutional unit (a1).

<<Constitutional Unit (a0)>>

The constitutional unit (a0) is a constitutional unit in which apolymerizable group at a W portion is converted into the main chain in acompound represented by Formula (a0-1). In a case where the component(A1) contains the constitutional unit (a0), the solubility duringdevelopment can be appropriately adjusted at the time of forming aresist film using the component (A1). Further, since the constitutionalunit (a0) contains an aromatic ring hydroxy group, this constitutionalunit becomes a proton source so that the sensitivity can be improved atthe time of formation of the resist pattern.

[In the formula, W represents a polymerizable group-containing group.Wa^(x0) represents an (n_(ax0)+1)-valent aromatic hydrocarbon groupwhich may have a substituent. n_(ax0) represents an integer of 1 to 3.]

In Formula (a0-1), W represents a polymerizable group-containing group.

The “polymerizable group” at the W portion indicates a group thatenables polymerization of a compound containing a polymerizable groupthrough radical polymerization or the like and also indicates a grouphaving multiple bonds between carbon atoms such as an ethylenic doublebond.

The “polymerizable group is converted into the main chain” indicatesthat the multiple bonds in the polymerizable group are cleaved to formthe main chain. For example, this indicates that in a case of a monomerhaving an ethylenic double bond, the ethylenic double bond is cleaved sothat a single bond between carbon atoms forms the main chain.

Examples of the polymerizable group at the W portion include a vinylgroup, an allyl group, an acryloyl group, a methacryloyl group, afluorovinyl group, a difluorovinyl group, a trifluorovinyl group, adifluorotrifluoromethylvinyl group, a trifluoroallyl group, aperfluoroallyl group, a trifluoromethylacryloyl group, anonylfluorobutylacryloyl group, a vinylether group, afluorine-containing vinyl ether group, an allylether group, afluorine-containing allyl ether group, a styryl group, a vinylnaphthylgroup, a fluorine-containing styryl group, a fluorine-containing vinylnaphthyl group, a norbomenyl group, a fluorine-containing norbomenylgroup, and a silyl group.

The polymerizable group-containing group may be a group formed of only apolymerizable group or a group formed of a polymerizable group andanother group other than the polymerizable group. Examples of anothergroup other than the polymerizable group include a divalent hydrocarbongroup which may have a substituent and a divalent linking group whichhas a hetero atom.

As a suitable example, W represents a group represented by ChemicalFormula: C(R^(X11))(R^(X12))═C(R^(X13))—Ya^(x0)-.

In this chemical formula, R^(X11), R^(X12), and R^(X13) each represent ahydrogen atom, an alkyl group having 1 to 5 carbon atoms, or ahalogenated alkyl group having 1 to 5 carbon atoms, and Ya^(x0)represents a single bond or a divalent linking group.

In the chemical formula, as the alkyl group having 1 to 5 carbon atomsas R^(X11), R^(X12), and R^(X13), a linear or branched alkyl grouphaving 1 to 5 carbon atoms is preferable, and specific examples thereofinclude a methyl group, an ethyl group, a propyl group, an isopropylgroup, an n-butyl group, an isobutyl group, a tert-butyl group, a pentylgroup, an isopentyl group, and a neopentyl group. The halogenated alkylgroup having 1 to 5 carbon atoms is a group in which some or allhydrogen atoms in the alkyl group having 1 to 5 carbon atoms have beensubstituted with halogen atoms. Examples of the halogen atom include afluorine atom, a chlorine atom, a bromine atom and an iodine atom, and afluorine atom is particularly preferable.

Among these, it is preferable that R^(X11) and R^(X12) each represent ahydrogen atom, an alkyl group having 1 to 5 carbon atoms, or afluorinated alkyl group having 1 to 5 carbon atoms. Further, from theviewpoint of industrial availability, R^(X11) and R^(X12) each representmore preferably a hydrogen atom or a methyl group and particularlypreferably a hydrogen atom.

Further, R^(X13) represents preferably a hydrogen atom, an alkyl grouphaving 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 5carbon atoms and more preferably, from the viewpoint of industrialavailability, a hydrogen atom or a methyl group.

In the chemical formula, the divalent linking group as Ya^(x0) is notparticularly limited, and examples thereof include a divalenthydrocarbon group which may have a substituent and a divalent linkinggroup having a hetero atom.

Divalent Hydrocarbon Group which May have Substituent:

In a case where Ya^(x0) represents a divalent hydrocarbon group whichmay have a substituent, the hydrocarbon group may be an aliphatichydrocarbon group or an aromatic hydrocarbon group.

Aliphatic Hydrocarbon Group as Ya^(x0)

The aliphatic hydrocarbon group indicates a hydrocarbon group that hasno aromaticity. The aliphatic hydrocarbon group may be saturated orunsaturated. In general, it is preferable that the aliphatic hydrocarbongroup is saturated.

Examples of the aliphatic hydrocarbon group include a linear or branchedaliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof.

Linear or Branched Aliphatic Hydrocarbon Group

The linear or branched aliphatic hydrocarbon group has preferably 1 to10 carbon atoms, more preferably 1 to 6 carbon atoms, still morepreferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄—], and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group has preferably 2 to 10 carbonatoms, more preferably 3 to 6 carbon atoms, still more preferably 3 or 4carbon atoms, and most preferably 3 carbon atoms.

As the branched aliphatic hydrocarbon group, a branched alkylene groupis preferred, and specific examples thereof include alkylalkylenegroups, for example, alkylmethylene groups such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and—C(CH₂CH₃)₂—; alkylethylene groups such as —CH(CH₃)CH₂—,—CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—;alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—;and alkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group in the alkylalkylene group, alinear alkyl group having 1 to 5 carbon atoms is preferable.

The linear or branched aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include a fluorine atom, afluorinated alkyl group having 1 to 5 carbon atoms which has beensubstituted with a fluorine atom, and a carbonyl group.

Aliphatic Hydrocarbon Group Containing Ring in Structure Thereof

Examples of the aliphatic hydrocarbon group containing a ring in thestructure thereof include a cyclic aliphatic hydrocarbon group which mayhave a substituent containing a hetero atom in the ring structurethereof (a group in which two hydrogen atoms have been removed from analiphatic hydrocarbon ring), a group in which the cyclic aliphatichydrocarbon group is bonded to the terminal of a linear or branchedaliphatic hydrocarbon group, and a group in which the cyclic aliphatichydrocarbon group is interposed in a linear or branched aliphatichydrocarbon group. As the linear or branched aliphatic hydrocarbongroup, the same groups as those described above can be exemplified.

The cyclic aliphatic hydrocarbon group has preferably 3 to 20 carbonatoms and more preferably 3 to 12 carbon atoms.

The cyclic aliphatic hydrocarbon group may be a polycyclic group or amonocyclic group. As the monocyclic alicyclic hydrocarbon group, a groupin which two hydrogen atoms have been removed from a monocycloalkane ispreferable. The monocycloalkane has preferably 3 to 6 carbon atoms, andspecific examples thereof include cyclopentane and cyclohexane. As thepolycyclic alicyclic hydrocarbon group, a group in which two hydrogenatoms have been removed from a polycycloalkane is preferable. As thepolycycloalkane, a group having 7 to 12 carbon atoms is preferable.Examples of the polycycloalkane include adamantane, norbornane,isobomane, tricyclodecane, and tetracyclododecane.

The cyclic aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup, and a carbonyl group.

The alkyl group as the substituent is preferably an alkyl group having 1to 5 carbon atoms, and a methyl group, an ethyl group, a propyl group,an n-butyl group, or a tert-butyl group is most preferable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group,an n-propoxy group, an iso-propoxy group, an n-butoxy group, or atert-butoxy group, and most preferably a methoxy group or an ethoxygroup.

Examples of the halogen atom as the substituent include a fluorine atom,a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atomis preferable.

Examples of the halogenated alkyl group as the substituent includegroups in which some or all hydrogen atoms in the above-described alkylgroups have been substituted with the above-described halogen atoms.

In the cyclic aliphatic hydrocarbon group, some carbon atomsconstituting the ring structure thereof may be substituted with asubstituent containing a hetero atom. As the substituent containing ahetero atom, —O—, —C(═O)—O—, —S—, —S(═O)₂—, or —S(═O)₂—O— is preferable.

Aromatic Hydrocarbon Group as Ya^(x0)

The aromatic hydrocarbon group is a hydrocarbon group having at leastone aromatic ring.

The aromatic ring is not particularly limited as long as it is a cyclicconjugated system having (4n+2) π electrons, and may be monocyclic orpolycyclic. The aromatic ring has preferably 5 to 30 carbon atoms, morepreferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbonatoms, and particularly preferably 6 to 12 carbon atoms. Here, thenumber of carbon atoms in a substituent is not included in the number ofcarbon atoms. Specific examples of the aromatic ring include aromatichydrocarbon rings such as benzene, naphthalene, anthracene, andphenanthrene; and aromatic hetero rings in which some carbon atomsconstituting the above-described aromatic hydrocarbon rings have beensubstituted with hetero atoms. Examples of the hetero atom in thearomatic hetero rings include an oxygen atom, a sulfur atom, and anitrogen atom. Specific examples of the aromatic hetero ring include apyridine ring and a thiophene ring.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the above-describedaromatic hydrocarbon ring or aromatic hetero ring (an arylene group or aheteroarylene group); a group in which two hydrogen atoms have beenremoved from an aromatic compound having two or more aromatic rings(such as biphenyl or fluorene); and a group in which one hydrogen atomof a group (an aryl group or a heteroaryl group) obtained by removingone hydrogen atom from the above-described aromatic hydrocarbon ring oraromatic hetero ring has been substituted with an alkylene group (forexample, a group obtained by further removing one hydrogen atom from anaryl group in an arylalkyl group such as a benzyl group, a phenethylgroup, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a1-naphthylethyl group, or a 2-naphthylethyl group). The number of carbonatoms in the alkylene group bonded to the aryl group or the heteroarylgroup is preferably in a range of 1 to 4, more preferably 1 or 2, andparticularly preferably 1.

With respect to the aromatic hydrocarbon group, the hydrogen atom in thearomatic hydrocarbon group may be substituted with a substituent. Forexample, the hydrogen atom bonded to the aromatic ring in the aromatichydrocarbon group may be substituted with a substituent. Examples ofsubstituents include an alkyl group, an alkoxy group, a halogen atom, ahalogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group having 1to 5 carbon atoms, and a methyl group, an ethyl group, a propyl group,an n-butyl group, or a tert-butyl group is more preferable.

As the alkoxy group, the halogen atom, and the halogenated alkyl groupas the substituents, the same groups as the above-described substituentgroups for substituting a hydrogen atom in the cyclic aliphatichydrocarbon group can be exemplified.

Divalent Linking Group Containing Hetero Atom

In a case where Ya^(x0) represents a divalent linking group containing ahetero atom, preferred examples of the linking group include —O—,—C(═O)—O—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH—, —NH—C(═NH)— (H may besubstituted with a substituent such as an alkyl group, an acyl group, orthe like), —S—, —S(═O)₂—, —S(═O)₂—O—, and a group represented byFormula: —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—,—[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²— or —Y²¹—S(═O)₂—O—Y²²— [inthe formulae, Y²¹ and Y²² each independently represent a divalenthydrocarbon group which may have a substituent, O represents an oxygenatom, and m″ represents an integer of 0 to 3].

In a case where the divalent linking group containing a hetero atom is—C(═O)—NH—, —C(═O)—NH—C(═O)—, —NH—, or —NH—C(═NH)—, H may be substitutedwith a substituent such as an alkyl group, an acyl group, or the like.The substituent (an alkyl group, an acyl group, or the like) haspreferably 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms,and most preferably 1 to 5 carbon atoms.

In Formula —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—,—[Y²¹—C(═O)—O]_(m″)—Y²²—, —Y²¹—O—C(═O)—Y²²—, or —Y²¹—S(═O)₂—O—Y²²—, Y²¹and Y²² each independently represent a divalent hydrocarbon group whichmay have a substituent. Examples of the divalent hydrocarbon groupinclude those (exemplified as the divalent hydrocarbon group which mayhave a substituent) in the description of the above-described divalentlinking group.

As Y²¹, a linear aliphatic hydrocarbon group is preferable, a linearalkylene group is more preferable, a linear alkylene group having 1 to 5carbon atoms is still more preferable, and a methylene group or anethylene group is particularly preferable.

As Y²², a linear or branched aliphatic hydrocarbon group is preferable,and a methylene group, an ethylene group, or an alkylmethylene group ismore preferable. The alkyl group in the alkylmethylene group ispreferably a linear alkyl group having 1 to 5 carbon atoms, morepreferably a linear alkyl group having 1 to 3 carbon atoms, and mostpreferably a methyl group.

In the group represented by Formula —[Y²¹—C(═O)—O]_(m″)—Y²²—, m″represents an integer of 0 to 3, preferably an integer of 0 to 2, morepreferably 0 or 1, and particularly preferably 1. In other words, it isparticularly preferable that the group represented by Formula—[Y²¹—C(═O)—O]_(m″)—Y²²— represents a group represented by Formula—Y²¹—C(═O)—O—Y²²—. Among these, a group represented by Formula—(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′represents an integer of 1 to 10, preferably an integer of 1 to 8, morepreferably an integer of 1 to 5, still more preferably 1 or 2, and mostpreferably 1. b′ represents an integer of 1 to 10, preferably an integerof 1 to 8, more preferably an integer of 1 to 5, still more preferably 1or 2, and most preferably 1.

It is preferable that Ya^(x0) represents an ester bond [—C(═O)—O— or—O—C(═O)—], an ether bond (—O—), a linear or branched alkylene group, ora combination thereof, or a single bond. Among these, an ester bond[—C(═O)—O— or —O—C(═O)—], a linear or branched alkylene group, or acombination thereof, or a single bond is more preferable, and a singlebond is particularly preferable.

In Formula (a0-1), Wa^(x0) represents an (n_(ax0)+1)-valent aromaticcyclic group which may have a substituent.

Examples of the aromatic cyclic hydrocarbon group as Wa^(x0) include agroup formed by removing (n_(ax0)+1) hydrogen atoms from an aromaticring. The aromatic ring is not particularly limited as long as it is acyclic conjugated system having (4n+2) it electrons, and may bemonocyclic or polycyclic. The aromatic ring has preferably 5 to 30carbon atoms, more preferably 5 to 20 carbon atoms, still morepreferably 6 to 15 carbon atoms, and particularly preferably 6 to 12carbon atoms. Specific examples of the aromatic ring include aromatichydrocarbon rings such as benzene, naphthalene, anthracene, andphenanthrene; and aromatic hetero rings in which some carbon atomsconstituting the above-described aromatic hydrocarbon rings have beensubstituted with hetero atoms. Examples of the hetero atom in thearomatic hetero rings include an oxygen atom, a sulfur atom, and anitrogen atom. Specific examples of the aromatic hetero ring include apyridine ring and a thiophene ring.

Examples of the substituent which may be included in Wa^(x) include acarboxy group, a halogen atom (such as a fluorine atom, a chlorine atom,or a bromine atom), an alkoxy group (such as a methoxy group, an ethoxygroup, a propoxy group, or a butoxy group), and an alkyloxycarbonylgroup.

In Formula (a0-1), Wa^(x0) may form a fused ring with W.

In a case where W and Wa^(x0) form a fused ring, examples of the ringstructure include a fused ring of an alicyclic hydrocarbon and anaromatic hydrocarbon. The fused ring formed by Wa^(x0) and W may have ahetero atom.

The moiety of the alicyclic hydrocarbon in the fused ring formed by Wand Wa^(x0) may be monocyclic or polycyclic.

Examples of the fused ring formed by W and Wa^(x0) include a fused ringformed by the polymerizable group at the W portion and Wa^(x0) and afused ring formed by a group other than the polymerizable group at the Wportion and Wa^(x0).

The fused ring formed by W and Wa^(x0) may have a substituent. Examplesof the substituent include a methyl group, an ethyl group, a propylgroup, a hydroxy group, a hydroxyalkyl group, a carboxy group, a halogenatom (such as a fluorine atom, a chlorine atom, or a bromine atom), analkoxy group (such as a methoxy group, an ethoxy group, a propoxy group,or a butoxy group), an acyl group, an alkyloxycarbonyl group, and analkyloxycarbonyloxy group.

Hereinafter, specific examples of the fused ring formed by W and Wa^(x)will be described. Wα represents a polymerizable group.

In Formula (a0-1), n_(ax0) represents an integer of 1 to 3, preferably 1or 2, and more preferably 1.

It is more preferable that the constitutional unit (a0) is aconstitutional unit (a011) represented by Formula (a0-11).

[In Formula (a0-11), R represents a hydrogen atom, an alkyl group having1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbons.Ya^(x01) represents a single bond or a divalent linking group. Wa^(x01)represents an (n_(ax01)+1)-valent aromatic hydrocarbon group which mayhave a substituent. n_(ax01) represents an integer of 1 to 3.]

In Formula (a0-11), R represents a hydrogen atom, an alkyl group having1 to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbonatoms.

As the alkyl group having 1 to 5 carbon atoms represented by R, a linearor branched alkyl group having 1 to 5 carbon atoms is preferable, andspecific examples thereof include a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group, and a neopentylgroup. The halogenated alkyl group having 1 to 5 carbon atoms as R is agroup in which some or all hydrogen atoms of the above-described alkylgroup having 1 to 5 carbon atoms have been substituted with halogenatoms. Examples of the halogen atom include a fluorine atom, a chlorineatom, a bromine atom, and an iodine atom, and a fluorine atom isparticularly preferable.

As R, a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or afluorinated alkyl group having 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is most preferable in terms ofindustrial availability.

In Formula (a0-11), Ya^(x01) represents a single bond or a divalentlinking group. Examples of the divalent linking group as Ya^(x01)include those exemplified as the divalent linking group as Ya^(x0) inFormula (a0-1).

In Formula (a0-11), it is preferable that Ya^(x01) represents a singlebond among the examples.

In Formula (a0-11), Wa^(x01) represents an (n_(ax01)+1)-valent aromatichydrocarbon group.

The aromatic hydrocarbon group as Wa^(x01) has the same definition asthe hydrocarbon group having at least one aromatic ring as Wa^(x0) inFormula (a0-1).

In Formula (a0-11), n_(ax01) represents an integer of 1 to 3, preferably1 or 2, and more preferably 1.

Hereinafter, specific examples of the constitutional unit represented bythe constitutional unit (a0) will be described.

In the following formulae, Rα represents a hydrogen atom, a methylgroup, or a trifluoromethyl group.

Among the examples shown above, the constitutional unit (a0) ispreferably at least one selected from the group consisting ofconstitutional units respectively represented by Chemical Formulae(a0-1-1) to (a0-1-26), more preferably at least one selected from thegroup consisting of constitutional unit respectively represented byChemical Formulae (a0-1-1) to (a0-1-7), still more preferably at leastone selected from the group consisting of constitutional unitsrespectively represented by Chemical Formulae (a0-1-1), (a0-1-2), and(a0-1-6), and particularly preferably a constitutional unit representedby Chemical Formula (a0-1-1).

The constitutional unit (a0) in the component (A1) may be used alone orin combination of two or more kinds thereof.

The proportion of the constitutional unit (a0) in the component (A1) ispreferably in a range of 10% to 70% by mole, more preferably in a rangeof 20% to 60% by mole, and still more preferably in a range of 30% to60% by mole with respect to the total amount (100% by mole) of allconstitutional units constituting the component (A1).

By setting the proportion of the constitutional unit (a0) to be greaterthan or equal to the lower limit of the above-described preferablerange, lithography characteristics of enhancing the sensitivity, theresolution, the roughness, and the like are improved.

Further, by setting the proportion of the constitutional unit (a0) to belower than or equal to the upper limit of the above-described preferablerange, the constitutional unit (a0) and other constitutional units canbe balanced, and the lithography characteristics are improved.

<<Constitutional Unit (a1)>>

The constitutional unit (a1) is a constitutional unit that contains anacid decomposable group whose polarity is increased due to the action ofan acid.

The term “acid decomposable group” indicates a group in which at least apart of a bond in the structure of the acid decomposable group can becleaved due to the action of an acid.

Examples of the acid decomposable group whose polarity is increased dueto the action of an acid include groups which are decomposed due to theaction of an acid to generate a polar group.

Examples of the polar group include a carboxy group, a hydroxyl group,an amino group, and a sulfo group (—SO₃H). Among these, a polar groupcontaining —OH in the structure thereof (hereinafter, also referred toas a “OH-containing polar group”) is preferable, a carboxy group or ahydroxyl group is more preferable, and a carboxy group is particularlypreferable.

More specific examples of the acid decomposable group include a group inwhich the above-described polar group has been protected with an aciddissociable group (such as a group in which a hydrogen atom of theOH-containing polar group has been protected with an acid dissociablegroup).

Here, the “acid dissociable group” indicates both (i) group in which abond between the acid dissociable group and an atom adjacent to the aciddissociable group can be cleaved due to the action of an acid; and (ii)group in which some bonds are cleaved due to the action of an acid, andthen a decarboxylation reaction occurs, thereby cleaving the bondbetween the acid dissociable group and the atom adjacent to the aciddissociable group.

It is necessary that the acid dissociable group that constitutes theacid decomposable group is a group which exhibits a lower polarity thanthe polar group generated by the dissociation of the acid dissociablegroup. Thus, in a case where the acid dissociable group is dissociatedby the action of an acid, a polar group exhibiting a higher polaritythan that of the acid dissociable group is generated, thereby increasingthe polarity. As a result, the polarity of the entire component (A1) isincreased. By the increase in the polarity, relatively, the solubilityin a developing solution changes, and the solubility in an alkalideveloping solution is increased, whereas the solubility in an organicdeveloping solution is relatively decreased.

Examples of the acid dissociable group are the same as those which havebeen proposed as acid dissociable groups for the base resin for achemically amplified resist composition.

Specific examples of acid dissociable groups of the base resin for aconventional chemically amplified resist composition include an“acetal-type acid dissociable group”, a “tertiary alkyl ester-type aciddissociable group”, and a “tertiary alkyloxycarbonyl acid dissociablegroup” described below.

Acetal-Type Acid Dissociable Group:

Examples of the acid dissociable group for protecting a carboxy group ora hydroxyl group as a polar group include the acid dissociable grouprepresented by Formula (a1-r-1) shown below (hereinafter, also referredto as an “acetal-type acid dissociable group”).

[In the formula, Ra′¹ and Ra′² represent a hydrogen atom or an alkylgroup, Ra′³ represents a hydrocarbon group, and Ra′³ may be bonded toany of Ra′¹ or Ra′² to form a ring.]

In Formula (a1-r-1), it is preferable that at least one of Ra′¹ and Ra′²represents a hydrogen atom and more preferable that both of Ra′¹ andRa′² represent a hydrogen atom.

In a case where Ra′¹ or Ra′² represents an alkyl group, examples of thealkyl group include the same alkyl groups exemplified as the substituentwhich may be bonded to the carbon atom at the α-position in thedescription on α-substituted acrylic acid ester. Among these, an alkylgroup having 1 to 5 carbon atoms is preferable. Specific examplesthereof include linear or branched alkyl groups. Specific examples ofthe alkyl group include a methyl group, an ethyl group, a propyl group,an isopropyl group, an n-butyl group, an isobutyl group, a tert-butylgroup, a pentyl group, an isopentyl group, and a neopentyl group. Amongthese, a methyl group or an ethyl group is preferable, and a methylgroup is particularly preferable.

In Formula (a1-r-1), examples of the hydrocarbon group as Ra′³ include alinear or branched alkyl group and a cyclic hydrocarbon group.

The linear alkyl group has preferably 1 to 5 carbon atoms, morepreferably 1 to 4 carbon atoms, and still more preferably 1 or 2 carbonatoms. Specific examples thereof include a methyl group, an ethyl group,an n-propyl group, an n-butyl group, and an n-pentyl group. Among these,a methyl group, an ethyl group, or an n-butyl group is preferable, and amethyl group or an ethyl group is more preferable.

The branched alkyl group has preferably 3 to 10 carbon atoms and morepreferably 3 to 5 carbon atoms. Specific examples thereof include anisopropyl group, an isobutyl group, a tert-butyl group, an isopentylgroup, a neopentyl group a 1,1-diethylpropyl group, and a2,2-dimethylbutyl group. Among these, an isopropyl group is preferable.

In a case where Ra′³ represents a cyclic hydrocarbon group, the cyclichydrocarbon group may be an aliphatic hydrocarbon group or an aromatichydrocarbon group, and may be a polycyclic group or a monocyclic group.

As the aliphatic hydrocarbon group which is a monocyclic group, a groupin which one hydrogen atom has been removed from a monocycloalkane ispreferable. The monocycloalkane has preferably 3 to 6 carbon atoms, andspecific examples thereof include cyclopentane and cyclohexane.

As the aliphatic hydrocarbon group which is a polycyclic group, a groupin which one hydrogen atom has been removed from a polycycloalkane ispreferable. As the polycycloalkane, a group having 7 to 12 carbon atomsis preferable, and specific examples of the polycycloalkane includeadamantane, norbornane, isobomane, tricyclodecane, andtetracyclododecane.

In a case where the cyclic hydrocarbon group as Ra′³ becomes an aromatichydrocarbon group, the aromatic hydrocarbon group is a hydrocarbon grouphaving at least one aromatic ring.

The aromatic ring is not particularly limited as long as it is a cyclicconjugated system having (4n+2) π electrons, and may be monocyclic orpolycyclic. The aromatic ring has preferably 5 to 30 carbon atoms, morepreferably 5 to 20 carbon atoms, still more preferably 6 to 15 carbonatoms, and most preferably 6 to 12 carbon atoms.

Specific examples of the aromatic ring include aromatic hydrocarbonrings such as benzene, naphthalene, anthracene, and phenanthrene; andaromatic hetero rings in which some carbon atoms constituting theabove-described aromatic hydrocarbon rings have been substituted withhetero atoms. Examples of the hetero atom in the aromatic hetero ringsinclude an oxygen atom, a sulfur atom, and a nitrogen atom. Specificexamples of the aromatic hetero ring include a pyridine ring and athiophene ring.

Specific examples of the aromatic hydrocarbon group as Ra′³ include agroup in which one hydrogen atom has been removed from theabove-described aromatic hydrocarbon ring or aromatic hetero ring (anaryl group or a heteroaryl group); a group in which one hydrogen atomhas been removed from an aromatic compound having two or more aromaticrings (biphenyl, fluorene or the like); and a group in which onehydrogen atom of the above-described aromatic hydrocarbon ring oraromatic hetero ring has been substituted with an alkylene group (anarylalkyl group such as a benzyl group, a phenethyl group, a1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-naphthylethylgroup, or a 2-naphthylethyl group). The number of carbon atoms in thealkylene group bonded to the aromatic hydrocarbon ring or aromatichetero ring is preferably in a range of 1 to 4, more preferably 1 or 2,and particularly preferably 1.

The cyclic hydrocarbon group as Ra′³ may include a substituent. Examplesof the substituent include —R^(P1), —R^(P2)—O—R^(P1), —R^(P2)—CO—R^(P1),—R^(P2)—CO—OR^(P1), —R^(P2)—O—CO—R^(P1), —R^(P2)—OH, —R^(P2)—CN, and—R^(P2)—COOH (hereinafter, these substituents will also be collectivelyreferred to as “Ra⁰⁵”).

Here, R^(P1) represents a chain-like monovalent saturated hydrocarbongroup having 1 to 10 carbon atoms, a monovalent aliphatic cyclicsaturated hydrocarbon group having 3 to 20 carbon atoms, or a monovalentaromatic hydrocarbon group having 6 to 30 carbon atoms. Further, R^(P2)represents a single bond, a chain-like divalent saturated hydrocarbongroup having 1 to 10 carbon atoms, a divalent aliphatic cyclic saturatedhydrocarbon group having 3 to 20 carbon atoms, or a divalent aromatichydrocarbon group having 6 to 30 carbon atoms.

Some or all hydrogen atoms in the chain-like saturated hydrocarbongroup, the aliphatic cyclic saturated hydrocarbon group, and thearomatic hydrocarbon group as R^(P1) and R^(P2) may be substituted withfluorine atoms. The aliphatic cyclic hydrocarbon group may have one ormore of one kind of substituents or one or more of each of plural kindsof the substituents.

Examples of the chain-like monovalent saturated hydrocarbon group having1 to 10 carbon atoms include a methyl group, an ethyl group, a propylgroup, a butyl group, a pentyl group, a hexyl group, a heptyl group, anoctyl group, and a decyl group.

Examples of the monovalent aliphatic cyclic saturated hydrocarbon grouphaving 3 to 20 carbon atoms include a monocyclic aliphatic saturatedhydrocarbon group such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, a cyclodecyl group, or a cyclododecyl group; and a polycyclicaliphatic saturated hydrocarbon group such as a bicyclo[2.2.2]octanylgroup, a tricyclo[5.2.1.02,6]decanyl group, atricyclo[3.3.1.13,7]decanyl group, atetracyclo[6.2.1.13,6.02,7]dodecanyl group, or an adamantyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 30carbon atoms include a group formed by removing one hydrogen atom froman aromatic hydrocarbon ring, such as benzene, biphenyl, fluorene,naphthalene, anthracene, or phenanthrene.

In a case where Ra′³ is bonded to Ra′¹ or Ra′² to form a ring, thecyclic group is preferably a 4- to 7-membered ring, and more preferablya 4- to 6-membered ring. Specific examples of the cyclic group include atetrahydropyranyl group and a tetrahydrofuranyl group.

Tertiary Alkyl Ester-Type Acid Dissociable Group:

Examples of the acid dissociable group for protecting the carboxy groupas a polar group include the acid dissociable group represented byFormula (a1-r-2) shown below.

Among the acid dissociable groups represented by Formula (a1-r-2), forconvenience, a group which is constituted of alkyl groups is referred toas “tertiary alkyl ester-type acid dissociable group”.

[In the formula, Ra′⁴ to Ra′⁶ each independently represent a hydrocarbongroup, provided that Ra′⁵ and Ra′⁶ may be bonded to each other to form aring.]

Examples of the hydrocarbon group as Ra′⁴ include a linear or branchedalkyl group, a chain-like or cyclic alkenyl group, and a cyclichydrocarbon group.

Examples of the linear or branched alkyl group and the cyclichydrocarbon group (an aliphatic hydrocarbon group which is a monocyclicgroup, an aliphatic hydrocarbon group which is a polycyclic group, or anaromatic hydrocarbon group) as Ra′⁴ are the same as those exemplifiedabove as Ra′³.

As the chain-like or cyclic alkenyl group as Ra′⁴, an alkenyl grouphaving 2 to 10 carbon atoms is preferable.

Examples of the hydrocarbon group as Ra′⁵ or Ra′⁶ are the same as thoseexemplified above as Ra′³.

In a case where Ra′⁵ and Ra′⁶ are bonded to form a ring, suitableexamples thereof include a group represented by Formula (a1-r2-1), agroup represented by Formula (a1-r2-2), and a group represented byFormula (a1-r2-3).

Meanwhile, in a case where Ra′⁴ to Ra′⁶ are not bonded to one anotherand represent an independent hydrocarbon group, suitable examplesthereof include a group represented by Formula (a1-r2-4).

[In Formula (a1-r2-1), Ra′¹⁰ represents an alkyl group having 1 to 10carbon atoms or a group represented by Formula (a1-r2-r1). Ra′¹¹represents a group that forms an aliphatic cyclic group together withthe carbon atom to which Ra′¹⁰ is bonded. In Formula (a1-r2-2), Yarepresents a carbon atom. Xa represents a group that forms a cyclichydrocarbon group together with Ya. Some or all hydrogen atoms in thiscyclic hydrocarbon group may be substituted. Ra⁰¹ to Ra⁰³ eachindependently represent a hydrogen atom, a chain-like monovalentsaturated hydrocarbon group having 1 to 10 carbon atoms, or a monovalentaliphatic cyclic saturated hydrocarbon group having 3 to 20 carbonatoms. Some or all hydrogen atoms in this chain-like saturatedhydrocarbon group and the aliphatic cyclic saturated hydrocarbon groupmay be substituted. Two or more of Ra⁰¹ to Ra⁰³ may be bonded to oneanother to form a cyclic structure. In Formula (a1-r2-3), Yaa representsa carbon atom. Xaa represents a group that forms an aliphatic cyclicgroup together with Yaa. Ra⁰⁴ represents an aromatic hydrocarbon groupwhich may have a substituent. In Formula (a1-r2-4), Ra′¹² and Ra′¹³ eachindependently represent a chain-like monovalent saturated hydrocarbonhaving 1 to 10 carbon atoms or a hydrogen atom. Some or all hydrogenatoms in this chain-like saturated hydrocarbon group may be substituted.Ra′¹⁴ represents a hydrocarbon group which may have a substituent. Thesymbol “*” represents a bonding site (the same applies hereinafter).]

[In the formula, Ya⁰ represents a quaternary carbon atom. Ra⁰³¹, Ra⁰³²,and Ra⁰³³ each independently represent a hydrocarbon group which mayhave a substituent. Here, one or more of Ra⁰³¹, Ra⁰³², and Ra⁰³³represent a hydrocarbon group containing at least one polar group.]

In Formula (a1-r2-1), as the alkyl group having 1 to 10 carbon atoms asRa′¹⁰, the groups exemplified as the linear or branched alkyl group asRa′³ in Formula (a1-r-1) are preferable. It is preferable that Ra′¹⁰represents an alkyl group having 1 to 5 carbon atoms.

In Formula (a1-r2-r1), Ya⁰ represents a quaternary carbon atom. That is,the number of adjacent carbon atoms bonded to Ya⁰ (carbon atom) is 4.

In Formula (a1-r2-r1), Ra⁰³¹, Ra⁰³², and Ra⁰³³ each independentlyrepresent a hydrocarbon group which may have a substituent. Thehydrocarbon groups as Ra⁰³¹, Ra⁰³², and Ra⁰³³ may each independently bea linear or branched alkyl group, a chain-like or cyclic alkenyl group,and a cyclic hydrocarbon group.

The number of carbon atoms in the linear alkyl group as Ra⁰³¹, Ra⁰³²,and Ra⁰³³ is preferably in a range of 1 to 5, more preferably in a rangeof 1 to 4, and still more preferably 1 or 2. Specific examples thereofinclude a methyl group, an ethyl group, an n-propyl group, an n-butylgroup, and an n-pentyl group. Among these, a methyl group, an ethylgroup, or an n-butyl group is preferable, and a methyl group or an ethylgroup is more preferable.

The number of carbon atoms in the branched alkyl group as Ra⁰³¹, Ra⁰³²,and Ra⁰³³ is preferably in a range of 3 to 10 and more preferably in arange of 3 to 5. Specific examples thereof include an isopropyl group,an isobutyl group, a tert-butyl group, an isopentyl group, a neopentylgroup a 1,1-diethylpropyl group, and a 2,2-dimethylbutyl group. Amongthese, an isopropyl group is preferable.

The number of chain-like or cyclic alkenyl group as Ra⁰³¹, Ra⁰³², andRa⁰³³ is preferably in a range of 2 to 10.

The cyclic hydrocarbon group as Ra⁰³¹, Ra⁰³², and Ra⁰³³ may be analiphatic hydrocarbon group or an aromatic hydrocarbon group and may bea polycyclic group or a monocyclic group.

As the aliphatic hydrocarbon group which is a monocyclic group, a groupin which one hydrogen atom has been removed from a monocycloalkane ispreferable. The monocycloalkane has preferably 3 to 6 carbon atoms, andspecific examples thereof include cyclopentane and cyclohexane.

As the aliphatic hydrocarbon group which is a polycyclic group, a groupin which one hydrogen atom has been removed from a polycycloalkane ispreferable. As the polycycloalkane, a group having 7 to 12 carbon atomsis preferable, and specific examples of the polycycloalkane includeadamantane, norbornane, isobomane, tricyclodecane, andtetracyclododecane.

The aromatic hydrocarbon group as Ra⁰³¹, Ra⁰³², and Ra⁰³³ is ahydrocarbon group having at least one aromatic ring. The aromatic ringis not particularly limited as long as it is a cyclic conjugated systemhaving (4n+2) π electrons, and may be monocyclic or polycyclic. Thearomatic ring has preferably 5 to 30 carbon atoms, more preferably 5 to20 carbon atoms, still more preferably 6 to 15 carbon atoms, andparticularly preferably 6 to 12 carbon atoms. Specific examples of thearomatic ring include aromatic hydrocarbon rings such as benzene,naphthalene, anthracene, and phenanthrene; and aromatic hetero rings inwhich some carbon atoms constituting the above-described aromatichydrocarbon rings have been substituted with hetero atoms. Examples ofthe hetero atom in the aromatic hetero rings include an oxygen atom, asulfur atom, and a nitrogen atom. Specific examples of the aromatichetero ring include a pyridine ring and a thiophene ring. Specificexamples of the aromatic hydrocarbon group include a group in which onehydrogen atom has been removed from the above-described aromatichydrocarbon ring or aromatic hetero ring (an aryl group or a heteroarylgroup); a group in which one hydrogen atom has been removed from anaromatic compound having two or more aromatic rings (such as biphenyl orfluorene); and a group in which one hydrogen atom of the above-describedaromatic hydrocarbon ring or aromatic hetero ring has been substitutedwith an alkylene group (for example, an arylalkyl group such as a benzylgroup, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethylgroup, a 1-naphthylethyl group, or a 2-naphthylethyl group). The numberof carbon atoms in the alkylene group bonded to the aromatic hydrocarbonring or aromatic hetero ring is preferably in a range of 1 to 4, morepreferably 1 or 2, and particularly preferably 1.

In a case where the hydrocarbon group represented by Ra⁰³¹, Ra⁰³², andRa⁰³³ is substituted, examples of the substituent include a hydroxygroup, a carboxy group, a halogen atom (such as a fluorine atom, achlorine atom, or a bromine atom), an alkoxy group (such as a methoxygroup, an ethoxy group, a propoxy group, or a butoxy group), and analkyloxycarbonyl group.

Among the examples, as the hydrocarbon group which may have asubstituent as Ra⁰³¹, Ra⁰³², and Ra⁰³³, a linear or branched alkyl groupwhich may have a substituent is preferable, and a linear alkyl group ismore preferable.

Here, one or more of Ra⁰³¹, Ra⁰³², and Ra⁰³³ represent a hydrocarbongroup containing at least a polar group.

The “hydrocarbon group containing a polar group” includes both of agroup in which a methylene group (—CH₂—) constituting a hydrocarbongroup is substituted with a polar group or a group in which at least onehydrogen atom constituting a hydrocarbon group is substituted with apolar group.

As such a “hydrocarbon group containing a polar group”, a functionalgroup represented by Formula (a1-p1) is preferable.

[In the formula, Ra⁰⁷ represents a divalent hydrocarbon group having 2to 12 carbon atoms. Ra⁰⁸ represents a divalent linking group having ahetero atom. Ra⁰⁶ represents a monovalent hydrocarbon group having 1 to12 carbon atoms. n_(p0) represents an integer of 1 to 6.]

In Formula (a1-p1), Ra⁰⁷ represents a divalent hydrocarbon group having2 to 12 carbon atoms.

The number of carbon atoms of Ra⁰⁷ is in a range of 2 to 12, preferablyin a range of 2 to 8, more preferably in a range of 2 to 6, still morepreferably in a range of 2 to 4, and particularly preferably 2.

As the hydrocarbon group represented by Ra⁰⁷, a chain-like or cyclicaliphatic hydrocarbon group is preferable, and a chain-like hydrocarbongroup is more preferable.

Examples of Ra⁰⁷ include a linear alkanediyl group such as an ethylenegroup, a propane-1,3-diyl group, a butane-1,4-diyl group, apentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diylgroup, an octane-1,8-diyl group, a nonane-1,9-diyl group, adecane-1,10-diyl group, an undecane-1,11-diyl group, or adodecane-1,12-diyl group; a branched alkanediyl group such as apropane-1,2-diyl group, a 1-methylbutane-1,3-diyl group, a2-methylpropane-1,3-diyl group, a pentane-1,4-diyl group, or a2-methylbutane-1,4-diyl group; a cycloalkanediyl group such as acyclobutane-1,3-diyl group, a cyclopentane-1,3-diyl group, acyclohexane-1,4-diyl group, or a cyclooctane-1,5-diyl group; and apolycyclic divalent alicyclic hydrocarbon group such as anorbomane-1,4-diyl group, a norbomane-2,5-diyl group, anadamantane-1,5-diyl group, or an adamantane-2,6-diyl group.

Among these, an alkanediyl group is preferable, and a linear alkanediylgroup is more preferable.

In Formula (a1-p1), Ra⁰⁸ represents a divalent linking group having ahetero atom.

Examples of Ra⁰⁸ include —O—, —C(═O)—O—, —C(═O)—, —O—C(═O)—O—,—C(═O)—NH—, —NH—, —NH—C(═NH)— (H may be substituted with a substituentsuch as an alkyl group or an acyl group), —S—, —S(═O)₂—, and —S(═O)₂—O—.

Among these, from the viewpoint of the solubility in a developingsolution, —O—, —C(═O)—O—, —C(═O)—, or —O—C(═O)—O— is preferable, and —O—or —C(═O)— is particularly preferable.

In Formula (a1-p1), Ra⁰⁶ represents a monovalent hydrocarbon grouphaving 1 to 12 carbon atoms.

The number of carbon atoms of Ra⁰⁶ is in a range of 1 to 12. From theviewpoint of the solubility in a developing solution, the number ofcarbon atoms thereof is preferably in a range of 1 to 8, more preferablyin a range of 1 to 5, still more preferably in a range of 1 to 3,particularly preferably 1 or 2, and most preferably 1.

Examples of the hydrocarbon group as Ra⁰⁶ include a chain-likehydrocarbon group, a cyclic hydrocarbon group, and a hydrocarbon groupobtained by combining a chain-like hydrocarbon group and a cyclichydrocarbon group.

Examples of the chain-like hydrocarbon group include a methyl group, anethyl group, an n-propyl group, an isopropyl group, an n-butyl group, asec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexylgroup, an n-heptyl group, a 2-ethylhexyl group, an n-octyl group, ann-nonyl group, an n-decyl group, an n-undecyl group, and an n-dodecylgroup.

The cyclic hydrocarbon group may be an alicyclic hydrocarbon group or anaromatic hydrocarbon group.

The alicyclic hydrocarbon group may be monocyclic or polycyclic, andexamples of the monocyclic alicyclic hydrocarbon group include acycloalkyl group such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, adimethylcyclohexyl group, a cycloheptyl group, a cyclooctyl group, acycloheptyl group, or a cyclodecyl group. Examples of the polycyclicalicyclic hydrocarbon group include a decahydronaphthyl group, anadamantyl group, a 2-alkyladamantane-2-yl group, a1-(adamantane-1-yl)alkane-1-yl group, a norbornyl group, amethylnorbonyl group, and an isobornyl group.

Examples of the aromatic hydrocarbon group include a phenyl group, anaphthyl group, an anthryl group, a p-methylphenyl group, ap-tert-butylphenyl group, a p-adamantylphenyl group, a tolyl group, axylyl group, a cumenyl group, a mesityl group, a biphenyl group, aphenanthryl group, a 2,6-diethylphenyl group, and a2-methyl-6-ethylphenyl group.

From the viewpoint of the solubility in a developing solution, Ra⁰⁶represents preferably a chain-like hydrocarbon group, more preferably analkyl group, and still more preferably a linear alkyl group.

In Formula (a1-p1), n_(p0) represents an integer of 1 to 6, preferablyan integer of 1 to 3, more preferably 1 or 2, and still more preferably1.

Hereinafter, specific examples of the hydrocarbon group containing atleast a polar group will be described.

In the formula shown below, the symbol “*” represents a bonding site tobe bonded to a quaternary carbon atom (Ya⁰).

In Formula (a1-r2-r1), among Ra⁰³¹, Ra⁰³², and Ra⁰³³, the number ofhydrocarbon groups containing at least a polar group is 1 or more andmay be appropriately determined in consideration of the solubility in adeveloping solution during formation of a resist pattern. For example,the number of hydrocarbon groups among Ra⁰³¹, Ra⁰³², and Ra⁰³³ ispreferably 1 or 2 and particularly preferably 1.

The hydrocarbon group containing at least a polar group may have asubstituent other than the polar group.

Examples of the substituent include a halogen atom (such as a fluorineatom, a chlorine atom, or a bromine atom) and a halogenated alkyl grouphaving 1 to 5 carbon atoms.

In Formula (a1-r2-1), preferred examples of Ra′¹¹ (an aliphatic cyclicgroup that is formed together with a carbon atom to which Ra′¹⁰ isbonded) include the groups exemplified as the aliphatic hydrocarbongroup which is a monocyclic group or a polycyclic group as Ra′³ inFormula (a1-r-1).

In Formula (a1-r2-2), as the cyclic hydrocarbon group that is formed byXa together with Ya, a group formed by further removing one or morehydrogen atoms from the cyclic monovalent hydrocarbon group (such as amonocyclic aliphatic hydrocarbon group, a polycyclic aliphatichydrocarbon group, or an aromatic hydrocarbon group) as Ra′³ in Formula(a1-r-1) is exemplified.

The cyclic hydrocarbon group that is formed by Xa together with Ya mayhave a substituent. Examples of the substituent are the same as thoseexemplified as the substituents which may be included in the cyclichydrocarbon group as Ra′³.

In Formula (a1-r2-2), examples of the chain-like monovalent hydrocarbongroup having 1 to 10 carbon atoms as Ra⁰¹ to Ra⁰³ include a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, and a decyl group.

Examples of the monovalent aliphatic cyclic saturated hydrocarbon grouphaving 3 to 20 carbon atoms as Ra⁰¹ to Ra⁰³ include a monocyclicaliphatic saturated hydrocarbon group such as a cyclopropyl group, acyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, a cyclooctyl group, a cyclodecyl group, or a cyclododecyl group;and a polycyclic aliphatic saturated hydrocarbon group such as abicyclo[2.2.2]octanyl group, a tricyclo[5.2.1.02,6]decanyl group, atricyclo[3.3.1.13,7]decanyl group, atetracyclo[6.2.1.13,6.02,7]dodecanyl group, or an adamantyl group. Fromthe viewpoint of easily synthesizing a monomer compound from which theconstitutional unit (a1) is derived, it is preferable that Ra⁰¹ to Ra⁰³represents a hydrogen atom or a chain-like monovalent saturatedhydrocarbon group having 1 to 10 carbon atoms. Among these, a hydrogenatom, a methyl group, or an ethyl group is more preferable, and ahydrogen atom is particularly preferable.

Examples of the substituent included in the cyclic saturated hydrocarbongroup or the aliphatic cyclic saturated hydrocarbon group represented byRa⁰¹ to Ra⁰³ are the same as those exemplified as Ra⁰⁵.

Examples of the group having a carbon-carbon double bond generated bytwo or more of Ra⁰¹ to Ra⁰³ being bonded to one another to form a cyclicstructure include a cyclopentenyl group, a cyclohexenyl group, amethylcyclopentenyl group, a methylcyclohexenyl group, acyclopentylidenethenyl group, and a cyclohexylidenethenyl group. Amongthese, from the viewpoint of easily synthesizing a monomer compound fromwhich the constitutional unit (a1) is derived, a cyclopentenyl group, acyclohexenyl group, or a cyclopentylidenethenyl group is preferable.

In Formula (a1-r2-3), as the aliphatic cyclic group that is formed byXaa together with Yaa, a group exemplified as the aliphatic hydrocarbongroup which is a monocyclic group or a polycyclic group as Ra′³ inFormula (a1-r-1) is preferable. In Formula (a1-r2-3), examples of thearomatic hydrocarbon group as Ra⁰⁴ include a group formed by removingone or more hydrogen atoms from an aromatic hydrocarbon ring having 5 to30 carbon atoms.

Among the examples, Ra⁰⁴ represents preferably a group formed byremoving one or more hydrogen atoms from an aromatic hydrocarbon ringhaving 6 to 15 carbon atoms, more preferably a group formed by removingone or more hydrogen atoms from benzene, naphthalene, anthracene, orphenanthrene, still more preferably a group formed by removing one ormore hydrogen atoms from benzene, naphthalene, or anthracene,particularly preferably a group formed by removing one or more hydrogenatoms from benzene or naphthalene, and most preferably a group formed byremoving one or more hydrogen atoms from benzene.

Examples of the substituent which may be included in Ra⁰⁴ in Formula(a1-r2-3) include a methyl group, an ethyl group, a propyl group, ahydroxyl group, a carboxyl group, a halogen atom (such as a fluorineatom, a chlorine atom, or a bromine atom), an alkoxy group (such as amethoxy group, an ethoxy group, a propoxy group, or a butoxy group), andan alkyloxycarbonyl group.

In Formula (a1-r2-4), Ra′¹² and Ra′¹³ each independently represent achain-like monovalent saturated hydrocarbon group having 1 to 10 carbonatoms or a hydrogen atom. Examples of the chain-like monovalentsaturated hydrocarbon group having 1 to 10 carbon atoms as Ra′¹² andRa′¹³ are the same as those exemplified as the chain-like monovalentsaturated hydrocarbon group having 1 to 10 carbon atoms as Ra⁰¹ to Ra⁰³.Some or all hydrogen atoms in the chain-like saturated hydrocarbon groupmay be substituted.

Ra′¹² and Ra′¹³ represent preferably a hydrogen atom or an alkyl grouphaving 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 5carbon atoms, still more preferably a methyl group or an ethyl group,and particularly preferably a methyl group. In a case where thechain-like saturated hydrocarbon group represented by Ra′¹² and Ra′¹³ issubstituted, examples of the substituent are the same as thoseexemplified as Ra⁰⁵.

In Formula (a1-r2-4), Ra′¹⁴ represents a hydrocarbon group which mayhave a substituent. Examples of the hydrocarbon group as Ra′¹⁴ include alinear or branched alkyl group and a cyclic hydrocarbon group.

The linear alkyl group as Ra′¹⁴ has preferably 1 to 5 carbon atoms, morepreferably 1 to 4 carbon atoms, and still more preferably 1 or 2 carbonatoms. Specific examples thereof include a methyl group, an ethyl group,an n-propyl group, an n-butyl group, and an n-pentyl group. Among these,a methyl group, an ethyl group, or an n-butyl group is preferable, and amethyl group or an ethyl group is more preferable.

The branched alkyl group as Ra′¹⁴ has preferably 3 to 10 carbon atomsand more preferably 3 to 5 carbon atoms. Specific examples thereofinclude an isopropyl group, an isobutyl group, a tert-butyl group, anisopentyl group, a neopentyl group a 1,1-diethylpropyl group, and a2,2-dimethylbutyl group. Among these, an isopropyl group is preferable.

In a case where Ra′¹⁴ represents a cyclic hydrocarbon group, thehydrocarbon group may be an aliphatic hydrocarbon group or an aromatichydrocarbon group, and may be polycyclic or monocyclic.

As the aliphatic hydrocarbon group which is a monocyclic group, a groupin which one hydrogen atom has been removed from a monocycloalkane ispreferable. The monocycloalkane has preferably 3 to 6 carbon atoms, andspecific examples thereof include cyclopentane and cyclohexane.

As the aliphatic hydrocarbon group which is a polycyclic group, a groupin which one hydrogen atom has been removed from a polycycloalkane ispreferable. As the polycycloalkane, a group having 7 to 12 carbon atomsis preferable, and specific examples of the polycycloalkane includeadamantane, norbomane, isobomane, tricyclodecane, andtetracyclododecane.

Examples of the aromatic hydrocarbon group as Ra′ 14 are the same asthose exemplified as the aromatic hydrocarbon group as Ra⁰⁴. Amongthese, Ra′¹⁴ represents preferably a group formed by removing one ormore hydrogen atoms from an aromatic hydrocarbon ring having 6 to 15carbon atoms, more preferably a group formed by removing one or morehydrogen atoms from benzene, naphthalene, anthracene, or phenanthrene,still more preferably a group formed by removing one or more hydrogenatoms from benzene, naphthalene, or anthracene, particularly preferablya group formed by removing one or more hydrogen atoms from naphthaleneor anthracene, and most preferably a group formed by removing one ormore hydrogen atoms from naphthalene.

Examples of the substituent which may be included in Ra′¹⁴ are the sameas those exemplified as the substituent which may be included in Ra⁰⁴.

In a case where Ra′¹⁴ in Formula (a1-r2-4) represents a naphthyl group,the position bonded to the tertiary carbon atom in Formula (a1-r2-4) maybe the 1-position or the 2-position of the naphthyl group.

In a case where Ra′¹⁴ in Formula (a1-r2-4) represents an anthryl group,the position bonded to the tertiary carbon atom in Formula (a1-r2-4) maybe the 1-position, the 2-position, or the 9-position of the anthrylgroup.

Specific examples of the group represented by Formula (a1-r2-1) areshown below.

Specific examples of the group represented by Formula (a1-r2-2) areshown below.

Specific examples of the group represented by Formula (a1-r2-3) areshown below.

Specific examples of the group represented by Formula (a1-r2-4) areshown below.

Tertiary Alkyloxycarbonyl Acid Dissociable Group:

Examples of the acid dissociable group for protecting a hydroxyl groupas a polar group include an acid dissociable group (hereinafter, forconvenience, also referred to as “tertiary alkyloxycarbonyl type aciddissociable group”) represented by Formula (a1-r-3) shown below.

[In the formula, Ra′⁷ to Ra′⁹ each independently represent an alkylgroup.]

In Formula (a1-r-3), Ra′⁷ to Ra′⁹ each independently representpreferably an alkyl group having 1 to 5 carbon atoms and more preferablyan alkyl group having 1 to 3 carbon atoms.

Further, the total number of carbon atoms in each alkyl group ispreferably in a range of 3 to 7, more preferably in a range of 3 to 5,and most preferably 3 or 4.

Examples of the constitutional unit (a1) include a constitutional unitderived from acrylic acid ester in which the hydrogen atom bonded to thecarbon atom at the α-position may be substituted with a substituent; aconstitutional unit derived from acrylamide; a constitutional unit inwhich at least some hydrogen atoms in a hydroxyl group of aconstitutional unit derived from hydroxystyrene or a hydroxystyrenederivative are protected by a substituent containing the aciddecomposable group; and a constitutional unit in which some hydrogenatoms in —C(═O)—OH of a constitutional unit derived from vinylbenzoicacid or a vinylbenzoic acid derivative are protected by a substituentcontaining the acid decomposable group.

Among the examples, as the constitutional unit (a1), a constitutionalunit derived from acrylic acid ester in which the hydrogen atom bondedto the carbon atom at the α-position may be substituted with asubstituent is preferable.

Specific preferred examples of such a constitutional unit (a1) includeconstitutional units represented by Formula (a1-1) or (a1-2) shownbelow.

[In the formula, R represents a hydrogen atom, an alkyl group having 1to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbonatoms. Va¹ represents a divalent hydrocarbon group which may contain anether bond. n_(a1) represents an integer of 0 to 2. Ra¹ represents anacid dissociable group represented by Formula (a1-r-1) or (a1-r-2). Wa¹represents a (n_(a2)+1)-valent hydrocarbon group, n_(a2) represents aninteger of 1 to 3, and Ra² represents an acid dissociable grouprepresented by Formula (a1-r-1) or (a1-r-3)].

In Formula (a1-1), as the alkyl group having 1 to 5 carbon atoms as R, alinear or branched alkyl group having 1 to 5 carbon atoms is preferable,and specific examples thereof include a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group, and a neopentylgroup. The halogenated alkyl group having 1 to 5 carbon atoms is a groupin which some or all hydrogen atoms of the above-described alkyl grouphaving 1 to 5 carbon atoms have been substituted with halogen atoms.Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom, and an iodine atom, and a fluorine atom is particularlypreferable.

As R, a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or afluorinated alkyl group having 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is most preferable in terms ofindustrial availability.

In Formula (a1-1), the divalent hydrocarbon group as Va¹ may be analiphatic hydrocarbon group or an aromatic hydrocarbon group.

The aliphatic hydrocarbon group as the divalent hydrocarbon grouprepresented by Va¹ may be saturated or unsaturated. In general, it ispreferable that the aliphatic hydrocarbon group is saturated.

As specific examples of the aliphatic hydrocarbon group, a linear orbranched aliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof.

The linear aliphatic hydrocarbon group has preferably 1 to 10 carbonatoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4carbon atoms, and most preferably 1 to 3 carbon atoms.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄—], and a pentamethylene group [—(CH₂)₅—].

The branched aliphatic hydrocarbon group has preferably 2 to 10 carbonatoms, more preferably 3 to 6 carbon atoms, still more preferably 3 or 4carbon atoms, and most preferably 3 carbon atoms.

As the branched aliphatic hydrocarbon group, a branched alkylene groupis preferred, and specific examples thereof include alkylalkylenegroups, for example, alkylmethylene groups such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and—C(CH₂CH₃)₂—; alkylethylene groups such as —CH(CH₃)CH₂—,—CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—;alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—;and alkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group in the alkylalkylene group, alinear alkyl group having 1 to 5 carbon atoms is preferable.

Examples of the aliphatic hydrocarbon group containing a ring in thestructure thereof include an alicyclic hydrocarbon group (a group inwhich two hydrogen atoms have been removed from an aliphatic hydrocarbonring), a group in which the alicyclic hydrocarbon group is bonded to theterminal of the above-described branched aliphatic hydrocarbon group,and a group in which the alicyclic hydrocarbon group is interposed inthe above-described linear or branched aliphatic hydrocarbon group. Thelinear or branched aliphatic hydrocarbon group is the same as definedfor the above-described linear aliphatic hydrocarbon group or theabove-described branched aliphatic hydrocarbon group.

The alicyclic hydrocarbon group has preferably 3 to 20 carbon atoms andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be monocyclic or polycyclic. As themonocyclic alicyclic hydrocarbon group, a group in which two hydrogenatoms have been removed from a monocycloalkane is preferable. Themonocycloalkane has preferably 3 to 6 carbon atoms, and specificexamples thereof include cyclopentane and cyclohexane. As the polycyclicalicyclic hydrocarbon group, a group in which two hydrogen atoms havebeen removed from a polycycloalkane is preferable. As thepolycycloalkane, a group having 7 to 12 carbon atoms is preferable.Specific examples of the polycycloalkane include adamantane, norbornane,isobomane, tricyclodecane, and tetracyclododecane.

The aromatic hydrocarbon group as the divalent hydrocarbon grouprepresented by Va¹ is a hydrocarbon group having an aromatic ring.

The aromatic hydrocarbon group has preferably 3 to 30 carbon atoms, morepreferably 5 to 30 carbon atoms, still more preferably 5 to 20 carbonatoms, particularly preferably 6 to 15 carbon atoms, and most preferably6 to 12 carbon atoms. Here, the number of carbon atoms in a substituentis not included in the number of carbon atoms.

Specific examples of the aromatic ring contained in the aromatichydrocarbon group include aromatic hydrocarbon rings such as benzene,biphenyl, fluorene, naphthalene, anthracene, and phenanthrene; andaromatic hetero rings in which some carbon atoms constituting theabove-described aromatic hydrocarbon rings have been substituted withhetero atoms. Examples of the hetero atom in the aromatic hetero ringsinclude an oxygen atom, a sulfur atom, and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the above-describedaromatic hydrocarbon ring (an arylene group); and a group in which onehydrogen atom of a group (an aryl group) formed by removing one hydrogenatom from the aromatic hydrocarbon ring has been substituted with analkylene group (a group formed by removing one more hydrogen atom froman aryl group in an arylalkyl group such as a benzyl group, a phenethylgroup, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a1-naphthylethyl group, or a 2-naphthylethyl group). The alkylene group(an alkyl chain in the arylalkyl group) has preferably 1 to 4 carbonatoms, more preferably 1 or 2 carbon atoms, and particularly preferably1 carbon atom.

In Formula (a1-1), Ra¹ represents an acid dissociable group representedby Formula (a1-r-1) or (a1-r-2).

In Formula (a1-2), the (n_(a2)+1)-valent hydrocarbon group as Wa¹ may bean aliphatic hydrocarbon group or an aromatic hydrocarbon group. Thealiphatic hydrocarbon group indicates a hydrocarbon group that has noaromaticity, and may be saturated or unsaturated. In general, it ispreferable that the aliphatic hydrocarbon group is saturated. Examplesof the aliphatic hydrocarbon group include a linear or branchedaliphatic hydrocarbon group, an aliphatic hydrocarbon group containing aring in the structure thereof, and a combination of the linear orbranched aliphatic hydrocarbon group and the aliphatic hydrocarbon groupcontaining a ring in the structure thereof.

The valency of n_(a2)+1 is preferably divalent, trivalent ortetravalent, and divalent or trivalent is more preferable.

In Formula (a1-2), Ra² represents an acid dissociable group representedby Formula (a1-r-1) or (a1-r-3).

Specific examples of the constitutional unit represented by Formula(a1-1) are shown below.

In the formulae shown below, R^(α) represents a hydrogen atom, a methylgroup, or a trifluoromethyl group.

Specific examples of the constitutional unit represented by Formula(a1-2) are shown below.

The constitutional unit (a1) included in the component (A1) may be usedalone or two or more kinds thereof.

Since the lithography characteristics (the sensitivity, the shape, andthe like) are easily improved using electron beams or EUV, aconstitutional unit represented by Formula (a1-1) is preferable as theconstitutional unit (a1).

Among the examples, as the constitutional unit (a1), those having aconstitutional unit represented by Formula (a1-1-1) are particularlypreferable.

[In the formulae, Ra¹″ represents an acid dissociable group representedby Formula (a1-r2-1). In Formula (a1-r2-1), Ra′10 represents an alkylgroup having 1 to 10 carbon atoms or a group represented by formula(a1-r2-r1).]

In Formula (a1-1-1), R, Va¹, and n_(a1) each have the same definition asthat for R, Va¹, and n_(a1) in Formula (a1-1).

The description of the acid dissociable group represented by Formula(a1-r2-1) is the same as the description above.

In Formula (a1-r2-1) in Formula (a1-1-1), among the examples, Ra′¹⁰represents preferably an alkyl group having 1 to 5 carbon atoms and morepreferably an alkyl group having 1 to 3 carbon atoms. Specific examplesof the alkyl group having 1 to 3 carbon atoms include a methyl group, anethyl group, an n-propyl group, and an isopropyl group.

In Formula (a1-r2-1) in Formula (a1-1-1), among the examples, Ra′¹¹ (analiphatic cyclic group formed with the carbon atom to which Ra′¹⁰ isbonded) represents preferably an aliphatic hydrocarbon group which is amonocyclic group and more preferably a group formed by removing onehydrogen atom from a monocycloalkane having 3 to 6 carbon atoms. Amongthese, a group formed by removing one hydrogen atom from a cyclopentaneis more preferable.

The proportion of the constitutional unit (a1) in the component (A1) ispreferably in a range of 5% to 80% by mole, more preferably in a rangeof 10% to 75% by mole, and still more preferably in a range of 30% to70% by mole with respect to the total amount (100% by mole) of allconstitutional units constituting the component (A1).

By setting the proportion of the constitutional unit (a1) to be greaterthan or equal to the lower limit of the above-described preferablerange, lithography characteristics of enhancing the sensitivity, theresolution, the roughness, and the like are improved. Further, bysetting the proportion of the constitutional unit (a1) to be lower thanor equal to the upper limit of the above-described preferable range, theconstitutional unit (a1) and other constitutional units can be balanced,and the lithography characteristics are improved.

<<Other Constitutional Units>>

The component (A1) may have constitutional units other than theconstitutional unit (a0) and the constitutional unit (a1).

Examples of other constitutional units include a constitutional unit(a2) (here, a constitutional unit corresponding to the constitutionalunit (a1) is excluded) containing a lactone-containing cyclic group, a—SO₂-containing cyclic group, or a carbonate-containing cyclic group, aconstitutional unit (a3) containing a polar group-containing aliphatichydrocarbon group, and a constitutional unit (a9) represented by Formula(a9-1).

<<Constitutional Unit (a2)>>

The component (A1) may have a constitutional unit (a2) (here, aconstitutional unit corresponding to the constitutional unit (a0) or theconstitutional unit (a1) is excluded) containing a lactone-containingcyclic group, a —SO₂-containing cyclic group, or a carbonate-containingcyclic group, in addition to the constitutional unit (a0) and theconstitutional unit (a1).

In a case where the component (A1) is used for forming a resist film,the lactone-containing cyclic group, the —SO₂-containing cyclic group,or the carbonate-containing cyclic group in the constitutional unit (a2)is effective for improving the adhesiveness of the resist film to thesubstrate. Further, in a case where the component (A1) contains theconstitutional unit (a2), the lithography characteristics and the likeare improved due to the effects of appropriately adjusting the aciddiffusion length, increasing the adhesiveness of the resist film to thesubstrate, and appropriately adjusting the solubility during thedevelopment.

The term “lactone-containing cyclic group” indicates a cyclic group thatcontains a ring (lactone ring) containing a —O—C(═O)— in the ringskeleton. In a case where the lactone ring is counted as the first ringand the group contains only the lactone ring, the group is referred toas a monocyclic group. Further, in a case where the group has other ringstructures, the group is referred to as a polycyclic group regardless ofthe structures. The lactone-containing cyclic group may be a monocyclicgroup or a polycyclic group.

The lactone-containing cyclic group for the constitutional unit (a2) isnot particularly limited, and an optional constitutional unit may beused. Specific examples thereof include groups represented by Formulae(a2-r-1) to (a2-r-7) shown below.

[In the formulae, each Ra′²¹ independently represents a hydrogen atom,an alkyl group, an alkoxy group, a halogen atom, a halogenated alkylgroup, a hydroxyl group, —COOR″, —OC(═O)R″, a hydroxyalkyl group, or acyano group; and R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group, ora —SO₂-containing cyclic group; A″ represents an oxygen atom (—O—), asulfur atom (—S—) or an alkylene group having 1 to 5 carbon atoms whichmay contain an oxygen atom or a sulfur atom; n′ represents an integer of0 to 2; and m′ represents 0 or 1.]

In Formulae (a2-r-1) to (a2-r-7), the alkyl group as Ra′²¹ is preferablyan alkyl group having 1 to 6 carbon atom. Further, the alkyl group ispreferably a linear alkyl group or a branched alkyl group. Specificexamples thereof include a methyl group, an ethyl group, a propyl group,an isopropyl group, an n-butyl group, an isobutyl group, a tert-butylgroup, a pentyl group, an isopentyl group, a neopentyl group and a hexylgroup. Among these, a methyl group or ethyl group is preferable, and amethyl group is particularly preferable.

The alkoxy group as Ra′²¹ is preferably an alkoxy group having 1 to 6carbon atoms.

Further, the alkoxy group is preferably a linear or branched alkoxygroup. Specific examples of the alkoxy groups include a group formed bylinking the above-described alkyl group exemplified as the alkyl grouprepresented by Ra′²¹ to an oxygen atom (—O—).

Examples of the halogen atom as Ra′²¹ include a fluorine atom, achlorine atom, a bromine atom, and an iodine atom. Among these, afluorine atom is preferable.

Examples of the halogenated alkyl group as Ra′²¹ include groups in whichsome or all hydrogen atoms in the above-described alkyl group as Ra′²¹have been substituted with the above-described halogen atoms. As thehalogenated alkyl group, a fluorinated alkyl group is preferable, and aperfluoroalkyl group is particularly preferable.

In —COOR″ and —OC(═O)R″ as Ra′²¹, R″ represents a hydrogen atom, analkyl group, a lactone-containing cyclic group, a carbonate-containingcyclic group, or a —SO₂-containing cyclic group.

The alkyl group as R″ may be linear, branched, or cyclic, and preferablyhas 1 to 15 carbon atoms.

In a case where R″ represents a linear or branched alkyl group, it ispreferably an alkyl group having 1 to 10 carbon atoms, more preferablyan alkyl group having 1 to 5 carbon atoms, and particularly preferably amethyl group or an ethyl group.

In a case where R″ represents a cyclic alkyl group, the number of carbonatoms thereof is preferably in a range of 3 to 15, more preferably in arange of 4 to 12, and most preferably in a range of 5 to 10.

Specific examples thereof include groups in which one or more hydrogenatoms have been removed from a monocycloalkane, which may or may not besubstituted with a fluorine atom or a fluorinated alkyl group; andgroups in which one or more hydrogen atoms have been removed from apolycycloalkane such as bicycloalkane, tricycloalkane, ortetracycloalkane. More specific examples thereof include groups in whichone or more hydrogen atoms have been removed from a monocycloalkane suchas cyclopentane or cyclohexane; and groups in which one or more hydrogenatoms have been removed from a polycycloalkane such as adamantane,norbornane, isobomane, tricyclodecane, or tetracyclododecane.

Examples of the lactone-containing cyclic group as R″ include thoseexemplified as the groups represented by Formulae (a2-r-1) to (a2-r-7).

The carbonate-containing cyclic group as R″ has the same definition asthat for the carbonate-containing cyclic group described below. Specificexamples of the carbonate-containing cyclic group include groupsrepresented by Formulae (ax3-r-1) to (ax3-r-3).

The —SO₂-containing cyclic group as R″ has the same definition as thatfor the —SO₂-containing cyclic group described below. Specific examplesof the —SO₂-containing cyclic group include groups represented byFormulae (a5-r-1) to (a5-r-4).

The hydroxyalkyl group as Ra′²¹ has preferably 1 to 6 carbon atoms, andspecific examples thereof include a group in which at least one hydrogenatom in the alkyl group as Ra′²¹ has been substituted with a hydroxylgroup.

In Formulae (a2-r-2), (a2-r-3) and (a2-r-5), as the alkylene grouphaving 1 to 5 carbon atoms as A″, a linear or branched alkylene group ispreferable, and examples thereof include a methylene group, an ethylenegroup, an n-propylene group, and an isopropylene group. Examples ofalkylene groups that contain an oxygen atom or a sulfur atom includegroups in which —O— or —S— is interposed in the terminal of the alkylenegroup or between the carbon atoms of the alkylene group, and examplesthereof include —O—CH₂—, —CH₂—O—CH₂—, —S—CH₂—, and —CH₂—S—CH₂—. As A″,an alkylene group having 1 to 5 carbon atoms or —O— is preferable, analkylene group having 1 to 5 carbon atoms is more preferable, and amethylene group is most preferable.

Specific examples of the groups represented by Formulae (a2-r-1) to(a2-r-7) are shown below.

The “—SO₂-containing cyclic group” indicates a cyclic group having aring containing —SO₂— in the ring skeleton thereof. Specifically, the—SO₂-containing cyclic group is a cyclic group in which the sulfur atom(S) in —SO₂— forms a part of the ring skeleton of the cyclic group. In acase where the ring containing —SO₂— in the ring skeleton thereof iscounted as the first ring and the group contains only the ring, thegroup is referred to as a monocyclic group. Further, in a case where thegroup has other ring structures, the group is referred to as apolycyclic group regardless of the structures. The —SO₂-containingcyclic group may be a monocyclic group or a polycyclic group.

As the —SO₂-containing cyclic group, a cyclic group containing —O—SO₂—in the ring skeleton thereof, in other words, a cyclic group containinga sultone ring in which —O—S— in the —O—SO₂— group forms a part of thering skeleton thereof is particularly preferable.

More specific examples of the —SO₂-containing cyclic group includegroups represented by Formulae (a5-r-1) to (a5-r-4) shown below.

[In the formulae, each Ra′⁵¹ independently represents a hydrogen atom,an alkyl group, an alkoxy group, a halogen atom, a halogenated alkylgroup, a hydroxyl group, —COOR″, —OC(═O)R″, a hydroxyalkyl group, or acyano group. R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group, ora —SO₂-containing cyclic group. A″ represents an oxygen atom, a sulfuratom or an alkylene group having 1 to 5 carbon atoms which may containan oxygen atom or a sulfur atom. n′ represents an integer of 0 to 2.]

In Formulae (a5-r-1) and (a5-r-2), A″ has the same definition as thatfor A″ in Formulae (a2-r-2), (a2-r-3) and (a2-r-5).

Examples of the alkyl group, the alkoxy group, the halogen atom, thehalogenated alkyl group, —COOR″, —OC(═O)R″, and the hydroxyalkyl groupas Ra′⁵¹ include the same groups as those described above in theexplanation of Ra′²¹ in Formulae (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by Formulae (a5-r-1) to(a5-r-4) are shown below. In the formulae shown below, “Ac” representsan acetyl group.

The “carbonate-containing cyclic group” indicates a cyclic group havinga ring (a carbonate ring) containing —O—C(═O)—O— in the ring skeletonthereof. In a case where the carbonate ring is counted as the first ringand the group contains only the carbonate ring, the group is referred toas a monocyclic group. Further, in a case where the group has other ringstructures, the group is referred to as a polycyclic group regardless ofthe structures. The carbonate-containing cyclic group may be amonocyclic group or a polycyclic group.

The carbonate ring-containing cyclic group is not particularly limited,and an optional group may be used. Specific examples thereof includegroups represented by Formulae (ax3-r-1) to (ax3-r-3) shown below.

[In the formulae, each Ra′^(x31) independently represents a hydrogenatom, an alkyl group, an alkoxy group, a halogen atom, a halogenatedalkyl group, a hydroxyl group, —COOR″, —OC(═O)R″, a hydroxyalkyl group,or a cyano group. R″ represents a hydrogen atom, an alkyl group, alactone-containing cyclic group, a carbonate-containing cyclic group, ora —SO₂-containing cyclic group. A″ represents an oxygen atom, a sulfuratom or an alkylene group having 1 to 5 carbon atoms which may containan oxygen atom or a sulfur atom. p′ represents an integer of 0 to 3, andq′ represents 0 or 1.]

In Formulae (ax3-r-2) and (ax3-r-3), A″ has the same definition as thatfor A″ in Formulae (a2-r-2), (a2-r-3) and (a2-r-5).

Examples of the alkyl group, the alkoxy group, the halogen atom, thehalogenated alkyl group, —COOR″, —OC(═O)R″, and the hydroxyalkyl groupas Ra′³¹ include the same groups as those described above in theexplanation of Ra′²¹ in Formulae (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by Formulae (ax3-r-1) to(ax3-r-3) are shown below.

As the constitutional unit (a2), a constitutional unit derived fromacrylic acid ester in which the hydrogen atom bonded to the carbon atomat the α-position may be substituted with a substituent is preferable.

It is preferable that such a constitutional unit (a2) is aconstitutional unit represented by Formula (a2-1).

[In the formula, R represents a hydrogen atom, an alkyl group having 1to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbonatoms. Ya²¹ represents a single bond or a divalent linking group. La²¹represents —O—, —COO—, —CON(R′)—, —OCO—, —CONHCO— or —CONHCS—, and R′represents a hydrogen atom or a methyl group. In a case where La²¹represents —O—, Ya²¹ does not represents —CO—. Ra²¹ represents alactone-containing cyclic group, a carbonate-containing cyclic group, ora —SO₂-containing cyclic group.]

In Formula (a2-1), R has the same definition as described above. As R, ahydrogen atom, an alkyl group having 1 to 5 carbon atoms, or afluorinated alkyl group having 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is particularly preferable in terms ofindustrial availability.

In Formula (a2-1), the divalent linking group as Ya²¹ is notparticularly limited, and suitable examples thereof include a divalenthydrocarbon group which may have a substituent and a divalent linkinggroup having hetero atoms. The divalent hydrocarbon group which may havea substituent and the divalent linking group having a hetero atom asYa²¹ each have the same definition as that for the divalent hydrocarbongroup which may have a substituent and the divalent linking group havinga hetero atom as Ya^(x1) in Formula (a10-1).

As Ya²¹, a single bond, an ester bond [—C(═O)—O—], an ether bond (—O—),a linear or branched alkylene group, or a combination of these ispreferable.

In Formula (a2-1), Ra²¹ represents a lactone-containing cyclic group, a—SO₂-containing cyclic group, or a carbonate-containing cyclic group.

Preferred examples of the lactone-containing cyclic group, the—SO₂-containing cyclic group, and the carbonate-containing cyclic groupas Ra²¹ include groups represented by Formulae (a2-r-1) to (a2-r-7),groups represented by Formulae (a5-r-1) to (a5-r-4), and groupsrepresented by Formulae (ax3-r-1) to (ax3-r-3).

Among the examples, Ra²¹ represents preferably a lactone-containingcyclic group or a —SO₂-containing cyclic group and more preferably agroup represented by Formula (a2-r-1), (a2-r-2), (a2-r-6) or (a5-r-1).Specifically, a group represented by any of Chemical Formulae (r-1c-1-1)to (r-1c-1-7), (r-1c-2-1) to (r-1c-2-18), (r-1c-6-1), (r-s1-1-1), and(r-s1-1-18) is more preferable, and a group represented by ChemicalFormula (r-1c-1-1) is still more preferable.

The constitutional unit (a2) included in the component (A1) may be usedalone or two or more kinds thereof.

In a case where the component (A1) has the constitutional unit (a2), theproportion of the constitutional unit (a2) in the component (A1) ispreferably in a range of 10% to 50% by mole, more preferably in a rangeof 5% to 45% by mole, still more preferably in a range of 10% to 40% bymole, and particularly preferably in a range of 10% to 30% by mole withrespect to the total amount (100% by mole) of all constitutional unitsconstituting the component (A1).

In a case where the proportion of the constitutional unit (a2) isgreater than or equal to the lower limit of the above-describedpreferable range, the effect obtained by allowing the component (A1) tocontain the constitutional unit (a2) can be satisfactorily achieved. Onthe contrary, in a case where the proportion of the constitutional unit(a2) is less than or equal to the upper limit of the above-describedpreferable range, the constitutional unit (a2) and other constitutionalunits can be balanced, and various lithography characteristics areimproved.

<<Constitutional Unit (a3)>>

The component (A1) may further have a constitutional unit (a3)containing a polar group-containing aliphatic hydrocarbon group (here, aconstitutional unit corresponding to any of the constitutional unit(a0), the constitutional unit (a1), or the constitutional unit (a2) isexcluded). Further, in a case where the component (A1) contains theconstitutional unit (a3), the lithography characteristics and the likeare improved due to the effects of appropriately adjusting the aciddiffusion length, increasing the adhesiveness of the resist film to thesubstrate, appropriately adjusting the solubility during thedevelopment, and improving the etching resistance.

Examples of the polar group include a hydroxyl group, a cyano group, acarboxy group, or a hydroxyalkyl group in which some hydrogen atoms ofthe alkyl group have been substituted with fluorine atoms. Among these,a hydroxyl group is particularly preferable.

Examples of the aliphatic hydrocarbon group include linear or branchedhydrocarbon groups (preferably alkylene groups) having 1 to 10 carbonatoms, and cyclic aliphatic hydrocarbon groups (cyclic groups). Thecyclic group may be a monocyclic group or a polycyclic group. Forexample, these cyclic groups can be selected appropriately from themultitude of groups that have been proposed for the resins of resistcompositions for ArF excimer lasers. The cyclic group is preferably apolycyclic group and more preferably a polycyclic group having 7 to 30carbon atoms.

Among the examples, constitutional units derived from acrylic acid esterthat include an aliphatic polycyclic group containing a hydroxyl group,cyano group, carboxy group, or a hydroxyalkyl group in which somehydrogen atoms of the alkyl group have been substituted with fluorineatoms are particularly preferable. Examples of the polycyclic groupinclude groups in which two or more hydrogen atoms have been removedfrom a bicycloalkane, tricycloalkane, tetracycloalkane or the like.Specific examples thereof include groups in which two or more hydrogenatoms have been removed from a polycycloalkane such as adamantane,norbomane, isobomane, tricyclodecane or tetracyclododecane. Among thesepolycyclic groups, groups in which two or more hydrogen atoms have beenremoved from adamantane, groups in which two or more hydrogen atoms havebeen removed from norbornane or groups in which two or more hydrogenatoms have been removed from tetracyclododecane are preferredindustrially.

The constitutional unit (a3) is not particularly limited as long as theconstitutional unit contains a polar group-containing aliphatichydrocarbon group, and an optional constitutional unit may be used.

The constitutional unit (a3) is a constitutional unit derived fromacrylic acid ester in which the hydrogen atom bonded to the carbon atomat the α-position may be substituted with a substituent, and aconstitutional unit containing a polar group-containing aliphatichydrocarbon group is preferable.

In a case where the hydrocarbon group in the polar group-containingaliphatic hydrocarbon group is a linear or branched hydrocarbon grouphaving 1 to 10 carbon atoms, a constitutional unit derived fromhydroxyethyl ester of acrylic acid is preferable as the constitutionalunit (a3).

Further, in a case where the hydrocarbon group in the polargroup-containing aliphatic hydrocarbon group is a polycyclic group, aconstitutional unit represented by Formula (a3-1), a constitutional unitrepresented by Formula (a3-2), and a constitutional unit represented byFormula (a3-3) are preferable, and a constitutional unit represented byFormula (a3-1) is more preferable as the constitutional unit (a3).

[In the formulae, R has the same definition as described above, jrepresents an integer of 1 to 3, k represents an integer of 1 to 3, t′represents an integer of 1 to 3, 1 represents an integer of 1 to 5, ands represents an integer of 1 to 3.]

In Formula (a3-1), j represents preferably 1 or 2 and more preferably 1.In a case where j represents 2, it is preferable that the hydroxylgroups is bonded to the 3rd- and 5-positions of the adamantyl group. Ina case where j represents 1, it is preferable that the hydroxyl group isbonded to the 3-position of the adamantyl group.

It is preferable that j represents 1, and it is particularly preferablethat the hydroxyl group is bonded to the 3-position of the adamantylgroup.

In Formula (a3-2), k represents preferably 1. The cyano group ispreferably bonded to the 5th or 6th position of the norbornyl group.

In Formula (a3-3), it is preferable that t′ represents 1. It ispreferable that 1 represents 1. It is preferable that s represents 1.Further, it is preferable that a 2-norbornyl group or 3-norbornyl groupis bonded to the terminal of the carboxy group of the acrylic acid. Itis preferable that the fluorinated alkyl alcohol is bonded to the 5- or6-position of the norbornyl group.

The constitutional unit (a3) included in the component (A1) may be usedalone or two or more kinds thereof.

In a case where the component (A1) has the constitutional unit (a2), theproportion of the constitutional unit (a2) in the component (A1) ispreferably in a range of 1% to 40% by mole, more preferably in a rangeof 2% to 30% by mole, still more preferably in a range of 5% to 25% bymole, and particularly preferably in a range of 5% to 20% by mole withrespect to the total amount (100% by mole) of all constitutional unitsconstituting the component (A1).

In a case where the proportion of the constitutional unit (a3) isgreater than or equal to the lower limit of the above-describedpreferable range, the effect obtained by allowing the component (A1) tocontain the constitutional unit (a3) can be satisfactorily achieved. Onthe contrary, in a case where the proportion of the constitutional unit(a3) is less than or equal to the upper limit of the above-describedpreferable range, the constitutional unit (a3) and other constitutionalunits can be balanced, and various lithography characteristics areimproved.

Constitutional Unit (a9):

The constitutional unit (a9) is a constitutional unit represented byFormula (a9-1).

[In the formula, R represents a hydrogen atom, an alkyl group having 1to 5 carbon atoms, or a halogenated alkyl group having 1 to 5 carbonatoms. Ya⁹¹ represents a single bond or a divalent linking group. Ya⁹²represents a divalent linking group. R⁹¹ represents a hydrocarbon groupwhich may have a substituent.]

In Formula (a9-1), R has the same definition as described above.

As R, a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or afluorinated alkyl group having 1 to 5 carbon atoms is preferable, and ahydrogen atom or a methyl group is particularly preferable in terms ofindustrial availability.

In Formula (a9-1), examples of the divalent linking group as Ya⁹¹include those exemplified as the divalent linking group represented byYa^(x1) in formula (a10-1). Among these, it is preferable that Ya⁹¹represents a single bond.

In Formula (a9-1), examples of the divalent linking group as Ya⁹²include those exemplified as the divalent linking group represented byYa^(x1) in formula (a10-1).

In the divalent linking group as Ya⁹², a linear or branched aliphatichydrocarbon group is preferable as the divalent hydrocarbon group whichmay have a substituent.

Further, in the divalent linking group as Ya⁹², examples of the divalentlinking group having a hetero atom include —O—, —C(═O)—O—, —C(═O)—,—O—C(═O)—O—, —C(═O)—NH—, —NH—, —NH—C(═NH)— (H may be substituted with asubstituent such as an alkyl group or an acyl group), —S—, —S(═O)₂—,—S(═O)₂—O—, and a group represented by Formula: —Y²¹—O—Y²²—, —Y²¹—O—,—Y²¹—C(═O)—O—, —C(═O)—O—Y²¹—, [Y²¹—C(═O)—O]_(m′)—Y²²—, or—Y²¹—O—C(═O)—Y²²— [in the formulae, Y²¹ and Y²² each independentlyrepresent a divalent hydrocarbon group which may have a substituent, Orepresents an oxygen atom, and m′ represents an integer of 0 to 3].Among these, —C(═O)— or —C(═S)— is preferable.

In Formula (a9-1), examples of the hydrocarbon group as R⁹¹ include analkyl group, a monovalent alicyclic hydrocarbon group, an aryl group,and an aralkyl group.

The alkyl group as R⁹¹ has preferably 1 to 8 carbon atoms, morepreferably 1 to 6 carbon atoms, and still more preferably 1 to 4 carbonatoms and may be linear or branched. Specific preferred examples thereofinclude a methyl group, an ethyl group, a propyl group, a butyl group, ahexyl group, and an octyl group.

The monovalent alicyclic hydrocarbon group as R⁹¹ has preferably 3 to 20carbon atoms and more preferably 3 to 12 carbon atoms and may bepolycyclic or monocyclic. As the monocyclic alicyclic hydrocarbon group,a group in which one or more hydrogen atoms have been removed from amonocycloalkane is preferable. It is preferable that the monocycloalkanehas 3 to 6 carbon atoms, and specific examples thereof includecyclobutane, cyclopentane, and cyclohexane. A group in which one or morehydrogen atoms have been removed from a polycycloalkane is preferable asthe polycyclic alicyclic hydrocarbon group. As the polycycloalkane, agroup having 7 to 12 carbon atoms is preferable, and specific examplesthereof include adamantane, norbomane, isobomane, tricyclodecane, andtetracyclododecane.

As the aryl group represented by R⁹¹, an aryl group having 6 to 18carbon atoms is preferable and an aryl group having 6 to 10 carbon atomsis more preferable. Specifically, a phenyl group is particularlypreferable.

As the aralkyl group represented by R⁹¹, an aralkyl group in which analkylene group having 1 to 8 carbon atoms are bonded to the “aryl groupas R⁹¹” is preferable, an aralkyl group in which an alkylene grouphaving 1 to 6 carbon atoms are bonded to the “aryl group as R⁹¹” is morepreferable, and an aralkyl group in which an alkylene group having 1 to4 carbon atoms are bonded to the “aryl group as R⁹¹” is particularlypreferable.

In the hydrocarbon group as R⁹¹, it is preferable that some or allhydrogen atoms in the hydrocarbon group are substituted with fluorineatoms and more preferable that 30% to 100% of hydrogen atoms in thehydrocarbon group are substituted with fluorine atoms. Among examples, aperfluoroalkyl group in which all hydrogen atoms in the alkyl group havebeen substituted with fluorine atoms is particularly preferable.

The hydrocarbon group as R⁹¹ may have a substituent. Examples of thesubstituent include a halogen atom, an oxo group (═O), a hydroxyl group(—OH), an amino group (—NH₂), and —SO₂—NH₂. Further, some carbon atomsconstituting the hydrocarbon group may be substituted with a substituenthaving a hetero atom. Examples of the substituent having a hetero atominclude —O—, —NH—, —N═, —C(═O)—O—, —S—, —S(═O)₂—, and —S(═O)₂—O—.

Examples of the hydrocarbon group having a substituent as R⁹¹ includelactone-containing cyclic groups respectively represented by Formulae(a2-r-1) to (a2-r-7).

Further, examples of the hydrocarbon group having a substituent as R⁹¹include —SO₂-containing cyclic groups respectively represented byFormulae (a5-r-1) to (a5-r-4), a substituted aryl group represented bythe following chemical formula, and a monovalent heterocyclic group.

Among examples of the constitutional unit (a9), a constitutional unitrepresented by Formula (a9-1-1) is preferable.

[In the formula, R has the same definition as described above, Ya⁹¹represents a single bond or a divalent linking group, R⁹¹ represents ahydrocarbon group which may have a substituent, and R⁹² represents anoxygen atom or a sulfur atom.]

In Formula (a9-1-1), Ya⁹¹, R⁹¹, and R each have the same definition asdescribed above.

Further, R⁹² represents an oxygen atom or a sulfur atom.

Hereinafter, specific examples of the constitutional unit represented byFormula (a9-1) or (a9-1-1) will be described. In the formulae, Rαrepresents a hydrogen atom, a methyl group, or a trifluoromethyl group.

The constitutional unit (a9) in the component (A1) may be used alone orin combination of two or more kinds thereof.

In a case where the component (A1) contains the constitutional unit(a9), the proportion of the constitutional unit (a9) is preferably in arange of 1% to 40% by mole, more preferably in a range of 3% to 30% bymole, still more preferably in a range of 5% to 25% by mole, andparticularly preferably in a range of 10% to 20% by mole with respect tothe total amount (100% by mole) of all constitutional units constitutingthe component (A1).

Further, in a case where the proportion of the constitutional unit (a9)is set to be greater than or equal to the lower limit of theabove-described preferable range, the effects of appropriately adjustingthe acid diffusion length, increasing the adhesiveness of the resistfilm to the substrate, appropriately adjusting the solubility during thedevelopment, and improving the etching resistance are obtained. Further,in a case where the proportion of the constitutional unit (a9) is set tobe less than or equal to the upper limit of the above-describedpreferable range, various lithography characteristics are improved.

The component (A1) contained in the resist composition may be used aloneor in combination of two or more kinds thereof.

In the resist composition of the present embodiment, the resin componentas the component (A1) has the constitutional unit (a0) and theconstitutional unit (a1) and may use a single polymer or two or morekinds of polymers in combination.

Suitable examples of the component (A1) include a component whichcontains a copolymer (hereinafter, this copolymer is referred to as a“component (A1-1)”) having the constitutional unit (a0) and theconstitutional unit (a1).

Further, examples of the component (A1) include a component (mixedresin) which contains a polymer having the constitutional unit (a0) andother constitutional unit as necessary and a polymer having theconstitutional unit (a1) and other constitutional units as necessary.

Among these, a component having the component (A1-1) is more preferableas the component (A1) contained in the resist composition.

Preferred examples of the component (A1-1) include a polymer compoundhaving a repeating structure of the constitutional unit (a0) and theconstitutional unit (a1) and a polymer compound having a repeating unitof the constitutional unit (a0), the constitutional unit (a1), and otherconstitutional units (the constitutional unit (a2)) or theconstitutional unit (a3).

The component (A1) can be produced by dissolving a monomer, from whicheach constitutional unit is derived, in a polymerization solvent andadding a radical polymerization initiator such as azobisisobutylonitrile(AIBN) or dimethyl azobisisobutyrate (for example, V-601) to thesolution so that the polymerization is carried out. Alternatively, sucha component (A1) can be produced by dissolving a monomer from which theconstitutional unit (a1) is derived and a precursor monomer (a monomerin which the functional group is protected) from which constitutionalunits other than the constitutional unit (a1) are derived as necessaryin a polymerization solvent, adding the above-described radicalpolymerization initiator to the solution, and performing a deprotectionreaction. Further, a —C(CF₃)₂—OH group may be introduced into theterminal of the component (A1) during the polymerization using a chaintransfer agent such as HS—CH₂—CH₂—CH₂—C(CF₃)₂—OH together. As describedabove, a copolymer into which a hydroxyalkyl group, formed bysubstitution of some hydrogen atoms in the alkyl group with fluorineatoms, has been introduced is effective for reducing development defectsand reducing line edge roughness (LER: uneven irregularities of a lineside wall).

The mass average molecular weight (Mw) (in terms of polystyreneaccording to gel permeation chromatography (GPC)) of the component (A1)is not particularly limited, but is preferably in a range of 1000 to50000, more preferably in a range of 2000 to 30000, and still morepreferably in a range of 3000 to 20000.

In a case where the Mw of the component (A1) is less than or equal tothe upper limit of the above-described preferable range, the resistcomposition exhibits a satisfactory solubility in a resist solvent for aresist enough to be used as a resist. On the other hand, in a case wherethe Mw of the component (A1) is greater than or equal to the lower limitof the above-described preferable range, dry etching resistance and thecross-sectional shape of the resist pattern become excellent.

Further, the dispersity (Mw/Mn) of the component (A1) is notparticularly limited, but is preferably in a range of 1.0 to 4.0, morepreferably in a range of 1.0 to 3.0, and particularly preferably in arange of 1.0 to 2.0. Further, Mn represents the number average molecularweight.

In Regard to Component (A2)

In the resist composition of the present embodiment, a base materialcomponent (hereinafter, referred to as a “component (A2)”) which doesnot correspond to the component (A1) and whose solubility in adeveloping solution is changed due to the action of an acid may be usedin combination as the component (A).

The component (A2) is not particularly limited, and may be optionallyselected from those known in the related art as the base materialcomponents for a chemically amplified resist composition.

In the component (A2), a polymer compound or a low molecular weightcompound may be used alone or in combination of two or more kindsthereof.

The proportion of the component (A1) in the component (A) is preferably25% by mass or greater, more preferably 50% by mass or greater, stillmore preferably 75% by mass or greater, and may be 100% by mass withrespect to the total mass of the component (A). In a case where theproportion of the component (A1) is 25% by mass or greater, a resistpattern with improved lithography characteristics, such as highsensitivity, the resolution, and roughness reduction, can be reliablyformed. Such effects are significantly exhibited particularly in thelithography using electron beams or EUV.

In the resist composition of the present embodiment, the content of thecomponent (A) may be appropriately adjusted according to the filmthickness of a resist intended to be formed.

<Compound (D0)>

In the resist composition according to the present embodiment, acomponent (D0) is a compound formed of an anion moiety and a cationmoiety which is represented by Formula (d0).

[In the formula, M^(m+) represents an m-valent organic cation. R^(d0)represents a substituent, p represents an integer of 0 to 3. In a casewhere p represents 2 or 3, a plurality of substituents as R^(d0) may bethe same as or different from one another. q represents an integer of 0to 3. n represents an integer of 2 or greater. Here, a relationship of“n+p≤(q×2)+5” is satisfied.]

In Regard to Anion Moiety

In Formula (d0), R^(d0) represents a substituent. Examples of thesubstituent include a hydrocarbon group, an alkoxy group, an acyl group,and a hydroxyalkyl group.

Examples of the hydrocarbon group as the substituent include a linear orbranched alkyl group, an aliphatic cyclic hydrocarbon group, and anaromatic hydrocarbon group.

As the linear or branched alkyl group, a linear or branched alkyl grouphaving 1 to 5 carbon atoms is preferable, and specific examples thereofinclude a methyl group, an ethyl group, a propyl group, an n-butylgroup, a tert-butyl group, and a pentyl group.

As the aliphatic cyclic hydrocarbon group, an aliphatic cyclichydrocarbon group having 3 to 6 carbon atoms is preferable, and specificexamples thereof include a cyclopropyl group, a cyclobutyl group, acyclopentyl group, and a cyclohexyl group.

As the aromatic hydrocarbon group, an aromatic hydrocarbon group having6 to 30 carbon atoms is preferable, and specific examples thereofinclude a group formed by removing one hydrogen atom from an aromatichydrocarbon ring such as benzene, biphenyl, fluorene, naphthalene,anthracene, or phenanthrene. Among these, a group (phenyl group) formedby removing one hydrogen atom from benzene is more preferable.

As the alkoxy group as the substituent, an alkoxy group having 1 to 5carbon atoms is preferable, and specific examples thereof include amethoxy group, an ethoxy group, a propoxy group, an n-butoxy group, atert-butoxy group, and a pentyloxy group. Among these, a methoxy groupis more preferable.

As the acyl group as the substituent, an acyl group having 1 to 3 carbonatoms is preferable, and specific examples thereof include a formylgroup, an acetyl group, and a propionyl group.

As the hydroxyalkyl group as the substituent, a hydroxyalkyl grouphaving 1 to 5 carbon atoms is preferable, and specific examples thereofinclude a hydroxymethyl group, a hydroxyethyl group, a hydroxypropylgroup, a hydroxybutyl group, and a hydroxypentyl group.

In Formula (d0), p represents an integer of 0 to 3. In a case where prepresents 2 or 3, a plurality of substituents as R^(d0) may be the sameas or different from one other. Among these, it is preferable that prepresents an integer of 0 to 2.

In Formula (d0), q represents an integer of 0 to 3. That is, in theanion moiety in Formula (d0), the structure becomes a benzene structurein a case where q represents 0, a naphthalene structure in a case whereq represents 1, an anthracene structure in a case where q represents 2,and a tetracene structure in a case where q represents 3. Further, therelationship of “n+p≤(q×2)+5” is satisfied. In other words, in thebenzene structure, the naphthalene structure, the anthracene structure,and the tetracene structure, all hydrogen atoms other than the hydrogenatoms substituted with the carboxylate group may be respectivelysubstituted with the above-described substituent or a hydroxy group.Here, the anion moiety in Formula (d0) contains at least two hydroxygroups.

Hereinafter, specific preferred examples of the anion moiety in thecomponent (D0) will be described.

Among the examples shown above, an anion represented by any of ChemicalFormulae (an-d0-1) to (an-d0-27) is more preferable, and an anionrepresented by any of Chemical Formulae (an-d0-2) to (an-d0-4) is stillmore preferable as the anion moiety in the component (D0).

In Regard to Cation Moiety ((M^(m+))_(1/m))

In Formula (d0), M^(m+) represents an m-valent organic cation. mrepresents an integer of 1 or greater.

Among the examples of the organic cation, a sulfonium cation or aniodonium cation is suitable example, and examples thereof includeorganic cations respectively represented by Formulae (ca-1) to (ca-4).

[In the formulae, R²⁰¹ to R²⁰⁷, R²¹¹, and R²¹² each independentlyrepresent an aryl group which may have a substituent, an alkyl groupwhich may have a substituent, or an alkenyl group which may have asubstituent. R²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷, and R²¹¹ and R²¹² may bebonded to each other to form a ring with the sulfur atom in the formula.R²⁰⁸ and R²⁰⁹ each independently represent a hydrogen atom or an alkylgroup having 1 to 5 carbon atoms or may be bonded to each other to forma ring with the sulfur atom in the formula. R²¹⁰ represents an arylgroup which may have a substituent, an alkyl group which may have asubstituent, an alkenyl group which may have a substituent, or a—SO₂-containing cyclic group which may have a substituent. L²⁰¹represents —C(═O)— or —C(═O)—O—. A plurality of Y²⁰¹'s eachindependently represent an arylene group, an alkylene group, or analkenylene group. x represents 1 or 2. W²⁰¹ represents a (x+1)-valentlinking group.]

Examples of the aryl group as R²⁰¹ to R²⁰⁷, R²¹¹, and R²¹² include anaryl group having 6 to 20 carbon atoms, and a phenyl group or a naphthylgroup is preferable.

The alkyl group as R²⁰¹ to R²⁰⁷, R²¹¹, and R²¹² is a chain-like orcyclic alkyl group, and the number of carbon atoms thereof is preferablyin a range of 1 to 30.

The alkenyl group as R²⁰¹ to R²⁰⁷, R²¹¹, and R²¹² preferably has 2 to 10carbon atoms.

Examples of the substituent which may be included in R²⁰¹ to R²⁰⁷, R²¹¹,and R²¹² include an alkyl group, a halogen atom, a halogenated alkylgroup, a carbonyl group, a cyano group, an amino group, an aryl group,and groups represented by Formulae (ca-r-1) to (ca-r-7) shown above.

[In the formulae, R′²⁰¹'s each independently represent a hydrogen atom,a cyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent, or a chain-like alkenyl group which mayhave a substituent.]

Examples of the cyclic group which may have a substituent, thechain-like alkyl group which may have a substituent, and the chain-likealkenyl group which may have a substituent as R′²⁰¹ are the same asthose represented by R¹⁰¹ in formula (b-1), and examples of the cyclicgroup which may have a substituent and the chain-like alkyl group whichmay have a substituent are the same as those exemplified as the aciddissociable group represented by Formula (a1-r-2).

R²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷, and R²¹¹ and R²¹² are bonded to each otherto form a ring with a sulfur atom in the formula, these groups may bebonded to one another via a hetero atom such as a sulfur atom, an oxygenatom or a nitrogen atom, or a functional group such as a carbonyl group,—SO—, —SO₂—, —SO₃—, —COO—, —CONH— or —N(RN)— (here, RN represents analkyl group having 1 to 5 carbon atoms). As a ring to be formed, a ringcontaining the sulfur atom in the formula in the ring skeleton thereofis preferably a 3- to 10-membered ring and most preferably a 5- to7-membered ring including the sulfur atom. Specific examples of the ringto be formed include a thiophene ring, a thiazole ring, a benzothiophenering, a thianthrene ring, a benzothiophene ring, a dibenzothiophenering, a 9H-thioxanthene ring, a thioxanthone ring, a phenoxathiin ring,a tetrahydrothiophenium ring, and a tetrahydrothiopyranium ring.

R²⁰⁸ and R²⁰⁹ each independently represent a hydrogen atom or an alkylgroup having 1 to 5 carbon atoms and preferably a hydrogen atom or analkyl group having 1 to 3 carbon atoms. In a case where R²⁰⁸ and R²⁰⁹each represents an alkyl group, R²⁰⁸ and R²⁰⁹ may be bonded to eachother to form a ring.

R²¹⁰ represents an aryl group which may have a substituent, an alkylgroup which may have a substituent, an alkenyl group which may have asubstituent, or a —SO₂-containing cyclic group which may have asubstituent.

Examples of the aryl group as R²¹⁰ include an unsubstituted aryl grouphaving 6 to 20 carbon atoms, and a phenyl group or a naphthyl group ispreferable.

As the alkyl group as R²¹⁰, a chain-like or cyclic alkyl group having 1to 30 carbon atoms is preferable.

The alkenyl group as R²¹⁰ preferably has 2 to 10 carbon atoms.

As the —SO₂-containing cyclic group as R²¹⁰ which may have asubstituent, the “—SO₂-containing polycyclic group” is preferable, and agroup represented by Formula (a5-r-1) is more preferable.

Y²⁰¹'s each independently represent an arylene group, an alkylene group,or an alkenylene group.

Examples of the arylene group as Y²⁰¹ include groups in which onehydrogen atom has been removed from an aryl group exemplified as thearomatic hydrocarbon group represented by R¹⁰¹ in Formula (b-1).

Examples of the alkylene group and alkenylene group as Y²⁰¹ includegroups in which one hydrogen atom has been removed from the chain-likealkyl group or the chain-like alkenyl group as R¹⁰¹ in Formula (b-1).

In Formula (ca-4), x represents 1 or 2.

W²⁰¹ represents a (x+1)-valent linking group, that is, a divalent ortrivalent linking group.

As the divalent linking group represented by W²⁰¹, a divalenthydrocarbon group which may have a substituent is preferable, and asexamples thereof, the same divalent hydrocarbon groups (which may have asubstituent) as those described above represented by Ya²¹ in Formula(a2-1) can be exemplified. The divalent linking group as W²⁰¹ may belinear, branched or cyclic, and cyclic is more preferable. Among these,an arylene group having two carbonyl groups, each bonded to the terminalthereof is preferable. Examples of the arylene group include a phenylenegroup, and a naphthylene group, and a phenylene group is particularlypreferable.

As the trivalent linking group as W²⁰¹, a group in which one hydrogenatom has been removed from the above-described divalent linking group asW²⁰¹ and a group in which the divalent linking group has been bonded toanother divalent linking group can be exemplified. The trivalent linkinggroup as W²⁰¹ is preferably a group in which two carbonyl groups arebonded to an arylene group.

Specific suitable examples of the cation represented by Formula (ca-1)include cations represented by Chemical Formulae (ca-1-1) to (ca-1-78)and (ca-1-101) to (ca-1-149) shown below.

In the following chemical formulae, g1 represents a repeating number,and g1 represents an integer of 1 to 5. g2 represents a repeatingnumber, and g2 represents an integer of 0 to 20. g3 represents arepeating number, and g3 represents an integer of 0 to 20.

[In the formulae, R″²⁰¹ represents a hydrogen atom or a substituent.Examples of the substituent include the alkyl group, the halogen atom,the halogenated alkyl group, the carbonyl group, the cyano group, theamino group, the aryl group, and the groups represented by Formulae(ca-r-1) to (ca-r-7), which are exemplified as the substituent which maybe included in R²⁰¹ to R²⁰⁷, R²¹¹, and R²¹².]

Specific examples of suitable cations represented by Formula (ca-2)include a cation represented by any of Formulae (ca-2-1) and (ca-2-2), adiphenyliodonium cation, and a bis(4-tert-butylphenyl)iodonium cation.

Specific examples of suitable cations represented by Formula (ca-3)include cations represented by Formulae (ca-3-1) to (ca-3-7) shownbelow.

Specific examples of suitable cations represented by Formula (ca-4)include cations represented by Formulae (ca-4-1) and (ca-4-2) shownbelow.

Among the examples, as the cation moiety ((M^(m+))_(1/m)), a cationrepresented by Formula (ca-1) is preferable. Specifically, a cationrepresented by any of Chemical Formulae (ca-1-1) to (ca-1-78) and(ca-1-101) to (ca-1-149) is more preferable, and a cation represented byFormula (ca-1-101) is still more preferable.

In the resist composition according to the present embodiment, it ismore preferable that the component (D0) is a compound formed of an anionmoiety and a cation moiety which is represented by Formula (d0-1).

[In the formula, R^(d1) represents an aryl group which may have asubstituent. R^(d2) and R^(d3) each independently represent an arylgroup which may have a substituent or may be bonded to each other toform a ring with a sulfur atom in the formula. R^(d0) represents asubstituent. p represents an integer of 0 to 3. In a case where prepresents 2 or 3, a plurality of substituents as R^(d0) may be the sameas or different from one another. q represents an integer of 0 to 3. nrepresents an integer of 2 or greater. Here, a relationship of“n+p≤(q×2)+5” is satisfied.]

In Formula (d0-1), the anion moiety has the same definition as describedin the section of Formula (d0). In Formula (d0-1), description of R^(d1)to R^(d3) is the same as described in the section of the aryl groupwhich may have a substituent as R²⁰¹ to R²⁰³ in Formula (ca-1). Further,description of the ring structure formed by R^(d2) and R^(d3) beingbonded to each other with a sulfur atom in the formula is the same asdescribed in the section of the ring structure formed by R²⁰¹ to R²⁰³ inFormula (ca-1) being bonded to each other with the sulfur atom in theformula.

Specific examples of the component (D0) include various compoundsobtained by combining cation moieties represented by any of ChemicalFormulae (ca-1-1) to (ca-1-78) and (ca-1-101) to (ca-1-149) and anionmoieties represented by any of Chemical Formulae (an-d0-1) to(an-d0-51). Among these, compounds obtained by combining a cation moietyrepresented by Chemical Formula (ca-1-101) and anion moietiesrepresented by any of Chemical Formulae (an-d0-2) to (an-d0-4) are morepreferable.

Hereinafter, specific examples of the component (D0) will be described,but the present invention is not limited thereto.

In the resist composition according to the present embodiment, thecomponent (D0) may be used alone or in combination of two or more kindsthereof.

The content of the component (D0) in the resist composition according tothe present embodiment is preferably in a range of 1 to 35 parts bymass, more preferably in a range of 2 to 25 parts by mass, still morepreferably in a range of 3 to 20 parts by mass, and particularlypreferably in a range of 3 to 15 parts by mass with respect to 100 partsby mass of the component (A).

In a case where the content of the component (D0) is greater than orequal to the lower limit of the above-described preferable range,excellent lithography characteristics (roughness reduction, theresolution, and the like) and excellent resist pattern shape are easilyobtained. Further, in a case where the content of the component (D0) isless than or equal to the upper limit of the above-described preferablerange, the component (D0) and other components can be balanced, andvarious lithography characteristics are improved.

<Optional Components>

The resist composition according to the present embodiment may furthercontain components (optional components) other than the component (A)and the component (D0) described above.

As such optional components, a component (B), a component (D) (here, acomponent corresponding to the component (D0) is excluded), a component(E), a component (F), and a component (S) described below areexemplified.

<<Component (B)>>

The component (B) is an acid generator component that generates an acidupon exposure.

The component (B) is not particularly limited, and those which have beenproposed as an acid generator for a chemically amplified resistcomposition in the related art can be used.

Examples of these acid generators are numerous and include oniumsalt-based acid generators such as iodonium salts and sulfonium salts;oxime sulfonate-based acid generators; diazomethane-based acidgenerators such as bisalkyl or bisaryl sulfonyl diazomethanes andpoly(bis-sulfonyl)diazomethanes; nitrobenzylsulfonate-based acidgenerators; iminosulfonate-based acid generators; and disulfone-basedacid generators.

Examples of the onium salt-based acid generators include a compoundrepresented by Formula (b-1) (hereinafter, also referred to as“component (b-1)”), a compound represented by Formula (b-2)(hereinafter, also referred to as “component (b-2)”), and a compoundrepresented by Formula (b-3) (hereinafter, also referred to as“component (b-3)”).

[In the formulae, R¹⁰¹ and R¹⁰⁴ to R¹⁰⁸ each independently represent acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent, or a chain-like alkenyl group which mayhave a substituent. R¹⁰⁴ and R¹⁰⁵ may be bonded to each other to form aring. R¹⁰² represents a fluorine atom or a fluorinated alkyl grouphaving 1 to 5 carbon atoms. Y¹⁰¹ represents a single bond or a divalentlinking group containing an oxygen atom. V¹⁰¹ to V¹⁰³ each independentlyrepresent a single bond, an alkylene group, or a fluorinated alkylenegroup. L¹⁰¹ and L¹⁰² each independently represent a single bond or anoxygen atom. L¹⁰³ to L¹⁰⁵ each independently represent a single bond,—CO— or —SO₂—. m represents an integer of 1 or greater, and M′^(m+)represents an m-valent onium cation.]

{Anion Moiety}

Anion Moiety of Component (b-1)

In Formula (b-1), R¹⁰¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent, or achain-like alkenyl group which may have a substituent.

Cyclic Group which May have Substituent:

The cyclic group is preferably a cyclic hydrocarbon group, and thecyclic hydrocarbon group may be an aromatic hydrocarbon group or analiphatic hydrocarbon group. The aliphatic hydrocarbon group indicates ahydrocarbon group that has no aromaticity. The aliphatic hydrocarbongroup may be saturated or unsaturated. In general, it is preferable thatthe aliphatic hydrocarbon group is saturated.

The aromatic hydrocarbon group as R¹⁰¹ is a hydrocarbon group having anaromatic ring. The aromatic hydrocarbon group has preferably 3 to 30carbon atoms, more preferably 5 to 30, still more preferably 5 to 20,particularly preferably 6 to 15, and most preferably 6 to 10. Here, thenumber of carbon atoms in a substituent is not included in the number ofcarbon atoms.

Specific examples of the aromatic ring contained in the aromatichydrocarbon group as R¹⁰¹ include benzene, fluorene, naphthalene,anthracene, phenanthrene, biphenyl, or an aromatic hetero ring in whichsome carbon atoms constituting any of these aromatic rings have beensubstituted with hetero atoms. Examples of the hetero atom in thearomatic hetero rings include an oxygen atom, a sulfur atom, and anitrogen atom.

Specific examples of the aromatic hydrocarbon group as R¹⁰¹ include agroup in which one hydrogen atom has been removed from theabove-described aromatic ring (an aryl group such as a phenyl group or anaphthyl group), and a group in which one hydrogen atom in the aromaticring has been substituted with an alkylene group (an arylalkyl groupsuch as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a2-naphthylmethyl group, 1-naphthylethyl group, or a 2-naphthylethylgroup). The alkylene group (an alkyl chain in the arylalkyl group) haspreferably 1 to 4 carbon atom, more preferably 1 or 2 carbon atoms, andparticularly preferably 1 carbon atom.

Examples of the cyclic aliphatic hydrocarbon group as R¹⁰¹ includealiphatic hydrocarbon groups containing a ring in the structure thereof.

Examples of the aliphatic hydrocarbon group containing a ring in thestructure thereof include an alicyclic hydrocarbon group (a group inwhich one hydrogen atom has been removed from an aliphatic hydrocarbonring), a group in which the alicyclic hydrocarbon group is bonded to theterminal of a linear or branched aliphatic hydrocarbon group, and agroup in which the alicyclic hydrocarbon group is interposed in a linearor branched aliphatic hydrocarbon group.

The alicyclic hydrocarbon group has preferably 3 to 20 carbon atoms andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be a polycyclic group or amonocyclic group. As the monocyclic alicyclic hydrocarbon group, a groupin which one or more hydrogen atoms have been removed from amonocycloalkane is preferable. The monocycloalkane has preferably 3 to 6carbon atoms, and specific examples thereof include cyclopentane andcyclohexane. As the polycyclic alicyclic hydrocarbon group, a group inwhich one or more hydrogen atoms have been removed from apolycycloalkane is preferable, and the number of carbon atoms of thepolycycloalkane is preferably in a range of 7 to 30. Amongpolycycloalkanes, a polycycloalkane having a bridged ring polycyclicskeleton, such as adamantane, norbomane, isobomane, tricyclodecane, ortetracyclododecane, and a polycycloalkane having a fused ring polycyclicskeleton, such as a cyclic group having a steroid skeleton arepreferable.

Among these examples, as the cyclic aliphatic hydrocarbon group as R¹⁰¹,a group in which one or more hydrogen atoms have been removed from amonocycloalkane or a polycycloalkane is preferable, a group in which onehydrogen atom has been removed from a polycycloalkane is morepreferable, an adamantyl group, or a norbornyl group is particularlypreferable, and an adamantyl group is most preferable.

The linear or branched aliphatic hydrocarbon group which may be bondedto the alicyclic hydrocarbon group has preferably 1 to 10 carbon atoms,more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbonatoms, and most preferably 1 to 3 carbon atoms.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable. Specific examples thereof include a methylene group [—CH₂—],an ethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄—], and a pentamethylene group [—(CH₂)₅—].

As the branched aliphatic hydrocarbon group, a branched alkylene groupis preferred, and specific examples thereof include alkylalkylenegroups, for example, alkylmethylene groups such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and—C(CH₂CH₃)₂—; alkylethylene groups such as —CH(CH₃)CH₂—,—CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, —CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—;alkyltrimethylene groups such as —CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—;and alkyltetramethylene groups such as —CH(CH₃)CH₂CH₂CH₂—, and—CH₂CH(CH₃)CH₂CH₂—. As the alkyl group in the alkylalkylene group, alinear alkyl group having 1 to 5 carbon atoms is preferable.

The cyclic hydrocarbon group as R¹⁰¹ may contain a hetero atom such as ahetero ring. Specific examples thereof include lactone-containing cyclicgroups represented by Formulae (a2-r-1) to (a2-r-7), the —SO₂-containingcyclic group represented by Formulae (a5-r-1) to (a5-r-4), and otherheterocyclic groups represented by Chemical Formulae (r-hr-1) to(r-hr-16).

Examples of the substituent for the cyclic group as R¹⁰¹ include analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, a carbonyl group, and a nitro group.

The alkyl group as the substituent is preferably an alkyl group having 1to 12 carbon atoms, and a methyl group, an ethyl group, a propyl group,an n-butyl group, or a tert-butyl group is most preferable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group,an n-propoxy group, an iso-propoxy group, an n-butoxy group, or atert-butoxy group, and most preferably a methoxy group or an ethoxygroup.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom, and an iodine atom, and afluorine atom is preferable.

Example of the above-described halogenated alkyl group as thesubstituent includes a group in which some or all hydrogen atoms in analkyl group having 1 to 5 carbon atoms such as a methyl group, an ethylgroup, a propyl group, an n-butyl group, or a tert-butyl group have beensubstituted with the above-described halogen atoms.

The carbonyl group as the substituent is a group that substitutes amethylene group (—CH₂—) constituting the cyclic hydrocarbon group.

Chain-Like Alkyl Group which May have Substituent:

The chain-like alkyl group as R¹⁰¹ may be linear or branched.

The linear alkyl group has preferably 1 to 20 carbon atoms, morepreferably 1 to 15 carbon atoms, and most preferably 1 to 10 carbonatoms.

Specific examples thereof include a methyl group, an ethyl group, apropyl group, a butyl group, a pentyl group, a hexyl group, a heptylgroup, an octyl group, a nonyl group, a decanyl group, an undecyl group,a dodecyl group, a tridecyl group, an isotridecyl group, a tetradecylgroup, a pentadecyl group, a hexadecyl group, an isohexadecyl group, aheptadecyl group, an octadecyl group, a nonadecyl group, an icosylgroup, a henicosyl group, and a docosyl group.

The branched alkyl group has preferably 3 to 20 carbon atoms, morepreferably 3 to 15, and most preferably 3 to 10. Specific examplesthereof include a 1-methylethyl group, a 1-methylpropyl group, a2-methylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a3-methylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group,and a 4-methylpentyl group.

Chain-Like Alkenyl Group which May have Substituent:

Such a chain-like alkenyl group as R¹⁰¹ may be linear or branched, andthe number of carbon atoms thereof is preferably in a range of 2 to 10,more preferably in a range of 2 to 5, still more preferably in a rangeof 2 to 4, and particularly preferably 3. Examples of the linear alkenylgroup include a vinyl group, a propenyl group (an allyl group), and abutynyl group. Examples of the branched alkenyl group include a1-methylvinyl group, a 2-methylvinyl group, a 1-methylpropenyl group,and a 2-methylpropenyl group.

Among the examples, as the chain-like alkenyl group, a linear alkenylgroup is preferable, a vinyl group or a propenyl group is morepreferable, and a vinyl group is particularly preferable.

As the substituent for the chain-like alkyl group or alkenyl group asR¹⁰¹, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxy group, a carbonyl group, a nitro group, an amino group, a cyclicgroup as R¹⁰¹ or the like can be used.

Among the examples, as R¹⁰¹, a cyclic group which may have a substituentis preferable, and a cyclic hydrocarbon group which may have asubstituent is more preferable. As the substituent, a hydroxy group, acarbonyl group, a nitro group, or an amino group is preferable. Amongthese, from the viewpoint of being easily distributed on the substrateside in the resist film, a hydroxy group is more preferable.

More specific preferred examples of the cyclic hydrocarbon group includea phenyl group, a naphthyl group, a group in which one or more hydrogenatoms have been removed from a polycycloalkane, a lactone-containingcyclic group represented by any of Formulae (a2-r-1) to (a2-r-7), and a—SO₂-containing cyclic group represented by any of Formulae (a5-r-1) to(a5-r-4).

In Formula (b-1), Y¹⁰¹ represents a single bond or a divalent linkinggroup containing an oxygen atom.

In a case where Y¹⁰¹ represents a divalent linking group containing anoxygen atom, Y^(O11) may contain an atom other than an oxygen atom.Examples of atoms other than an oxygen atom include a carbon atom, ahydrogen atom, a sulfur atom, and a nitrogen atom.

Examples of divalent linking groups containing an oxygen atom includenon-hydrocarbon oxygen atom-containing linking groups such as an oxygenatom (an ether bond; —O—), an ester bond (—C(═O)—O—), an oxycarbonylgroup (—O—C(═O)—), an amide bond (—C(═O)—NH—), a carbonyl group(—C(═O)—), or a carbonate bond (—O—C(═O)—O—); and combinations of theabove-described non-hydrocarbon oxygen atom-containing linking groupswith an alkylene group. Furthermore, a sulfonyl group (—SO₂—) may belinked to the combination. Examples of divalent linking groupscontaining an oxygen atom include linking groups represented by Formulae(y-a1-1) to (y-a1-7) shown below.

[In the formulae, V′¹⁰¹ represents a single bond or an alkylene grouphaving 1 to 5 carbon atoms, and V′¹⁰² represents a divalent saturatedhydrocarbon group having 1 to 30 carbon atoms.]

The divalent saturated hydrocarbon group as V′¹⁰² is preferably analkylene group having 1 to 30 carbon atoms, more preferably an alkylenegroup having 1 to 10 carbon atoms, and still more preferably an alkylenegroup having 1 to 5 carbon atoms.

The alkylene group as V′¹⁰¹ and V′¹⁰² may be a linear alkylene group ora branched alkylene group, and a linear alkylene group is preferable.

Specific examples of the alkylene group as V′¹⁰¹ and V′¹⁰² include amethylene group [—CH₂—]; an alkylmethylene group such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, or—C(CH₂CH₃)₂—; an ethylene group [—CH₂CH₂—]; an alkylethylene group suchas —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—, or —CH(CH₂CH₃)CH₂—; atrimethylene group (n-propylene group) [—CH₂CH₂CH₂—]; analkyltrimethylene group such as —CH(CH₃)CH₂CH₂— or —CH₂CH(CH₃)CH₂—; atetramethylene group [—CH₂CH₂CH₂CH₂—]; an alkyltetramethylene group suchas —CH(CH₃)CH₂CH₂CH₂—, —CH₂CH(CH₃)CH₂CH₂—; and a pentamethylene group[—CH₂CH₂CH₂CH₂CH₂—].

Further, a part of methylene group in the alkylene group as V′¹⁰¹ andV′¹⁰² may be substituted with a divalent aliphatic cyclic group having 5to 10 carbon atoms. The aliphatic cyclic group is preferably a divalentgroup in which one hydrogen atom has been removed from the cyclicaliphatic hydrocarbon group (a monocyclic aliphatic hydrocarbon group ora polycyclic aliphatic hydrocarbon group) as Ra′³ in Formula (a1-r-1),and a cyclohexylene group, a 1,5-adamantylene group, or a2,6-adamantylene group is more preferable.

Y¹⁰¹ represents preferably a divalent linking group containing an esterbond or a divalent linking group containing an ether bond and morepreferably linking groups represented by Formulae (y-a1-1) to (y-a1-5).

In Formula (b-1), V¹⁰¹ represents a single bond, an alkylene group, or afluorinated alkylene group. The alkylene group and the fluorinatedalkylene group as V¹⁰¹ preferably have 1 to 4 carbon atoms. Examples ofthe fluorinated alkylene group as V¹⁰¹ include a group in which some orall hydrogen atoms in the alkylene group as V¹⁰¹ have been substitutedwith fluorine atoms. Among these examples, as V¹⁰¹, a single bond or afluorinated alkylene group having 1 to 4 carbon atoms is preferable.

In Formula (b-1), R¹⁰² represents a fluorine atom or a fluorinated alkylgroup having 1 to 5 carbon atoms. R¹⁰² represents preferably a fluorineatom or a perfluoroalkyl group having 1 to 5 carbon atoms and morepreferably a fluorine atom.

As a specific example of the anion moiety for the component (b-1), in acase where Y¹⁰¹ represents a single bond, a fluorinated alkylsulfonateanion such as a trifluoromethanesulfonate anion or aperfluorobutanesulfonate anion can be exemplified; and in a case whereY¹⁰¹ represents a divalent linking group containing an oxygen atom,anions represented by Formulae (an-1) to (an-3) shown below can beexemplified.

[In the formulae, R″¹⁰¹ represents an aliphatic cyclic group which mayhave a substituent, a group represented by any of Formulae (r-hr-1) to(r-hr-6), or a chain-like alkyl group which may have a substituent.R″¹⁰² represents an aliphatic cyclic group which may have a substituent,a lactone-containing cyclic group represented by any of Formulae(a2-r-1) to (a2-r-7), or a —SO₂-containing cyclic group represented byany of Formulae (a5-r-1) to (a5-r-4). R″¹⁰³ represents an aromaticcyclic group which may have a substituent, an aliphatic cyclic groupwhich may have a substituent, or a chain-like alkenyl group which mayhave a substituent. V″¹⁰¹ represents a single bond, an alkylene grouphaving 1 to 4 carbon atoms, or a fluorinated alkylene group having 1 to4 carbon atoms. R¹⁰² represents a fluorine atom or a fluorinated alkylgroup having 1 to 5 carbon atoms. Each v″ independently represents aninteger of 0 to 3, each q″ independently represents an integer of 1 to20, and n″ represents 0 or 1.]

As the aliphatic cyclic group as R″¹⁰¹, R″¹⁰², and R″¹⁰³ which may havea substituent, the same groups as the cyclic aliphatic hydrocarbon groupas R¹⁰¹ described above are preferable.

As the substituent, the same groups as the substituents which maysubstitute the cyclic aliphatic hydrocarbon group as R¹⁰¹ can beexemplified. Among these, a hydroxy group, a carbonyl group, a nitrogroup, or an amino group is preferable. Among these, from the viewpointof being easily distributed on the substrate side in the resist film, ahydroxy group is more preferable.

As the aromatic cyclic group as R″¹⁰³ which may have a substituent, thesame groups as the aromatic hydrocarbon group for the cyclic hydrocarbongroup represented by R¹⁰¹ described above are preferable. As thesubstituent, the same groups as the substituents which may substitutethe aromatic hydrocarbon group as R¹⁰¹ can be exemplified.

As the chain-like alkyl group as R″¹⁰¹ which may have a substituent, thesame groups exemplified as the chain-like alkyl groups represented byR¹⁰¹ are preferable. As the chain-like alkenyl group as R″¹⁰³ which mayhave a substituent, the same groups exemplified as the chain-likealkenyl groups represented by R¹⁰¹ are preferable.

In Formulae (an-1) to (an-3), V″¹⁰¹ represents a single bond, analkylene group having 1 to 4 carbon atoms, or a fluorinated alkylenegroup having 1 to 4 carbon atoms. It is preferable that V″¹⁰¹ representsa single bond, an alkylene group having 1 carbon atom (methylene group),or a fluorinated alkylene group having 1 to 3 carbon atoms.

In Formulae (an-1) to (an-3), R¹⁰² represents a fluorine atom or afluorinated alkyl group having 1 to 5 carbon atoms. R¹⁰² representspreferably a perfluoroalkyl group having 1 to 5 carbon atoms or afluorine atom and more preferably a fluorine atom.

In Formulae (an-1) to (an-3), v″ represents an integer of 0 to 3 andpreferably 0 or 1. q″ represents an integer of 1 to 20, preferably aninteger of 1 to 10, more preferably an integer of 1 to 5, still morepreferably 1, 2, or 3, and particularly preferably 1 or 2. n″ represents0 or 1.

Anion Moiety of Component (b-2)

In Formula (b-2), R¹⁰⁴ and R¹⁰⁵ each independently represent a cyclicgroup which may have a substituent, a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent, and has the same definition as that for R¹⁰¹ in Formula(b-1). R¹⁰⁴ and R¹⁰⁵ may be bonded to each other to form a ring.

As R¹⁰⁴ and R¹⁰⁵, a chain-like alkyl group which may have a substituentis preferable, and a linear or branched alkyl group or a linear orbranched fluorinated alkyl group is more preferable.

The chain-like alkyl group has preferably 1 to 10 carbon atoms, morepreferably 1 to 7 carbon atoms, and still more preferably 1 to 3 carbonatoms. It is preferable that the number of carbon atoms in thechain-like alkyl group as R¹⁰⁴ and R¹⁰⁵ is small because the solubilityin a solvent for a resist is also excellent in the range of the numberof carbon atoms. Further, in the chain-like alkyl group as R¹⁰⁴ andR¹⁰⁵, it is preferable that the number of hydrogen atoms substitutedwith fluorine atoms is as large as possible because the acid strengthincreases and the transparency to high energy radiation of 200 nm orless or electron beams is improved.

The proportion of fluorine atoms in the chain-like alkyl group, that is,the fluorination ratio is preferably in a range of 70% to 100% and morepreferably in a range of 90% to 100%, and it is most preferable that thechain-like alkyl group is a perfluoroalkyl group in which all hydrogenatoms are substituted with fluorine atoms.

In Formula (b-2), V¹⁰² and V¹⁰³ each independently represent a singlebond, an alkylene group, or a fluorinated alkylene group, and has thesame definition as that for V¹⁰¹ in Formula (b-1).

In Formula (b-2), L¹⁰¹ and L¹⁰² each independently represent a singlebond or an oxygen atom.

Anion Moiety of Component (b-3)

In Formula (b-3), R¹⁰⁶ to R¹⁰⁸ each independently represent a cyclicgroup which may have a substituent or a chain-like alkyl group which mayhave a substituent or a chain-like alkenyl group which may have asubstituent, and has the same definition as that for R¹⁰¹ in Formula(b-1).

L¹⁰³ to L¹⁰⁵ each independently represent a single bond, —CO—, or —SO₂—.

{Cation Moiety}

In Formulae (b-1), (b-2), and (b-3), m represents an integer of 1 orgreater, and M′^(m+) represents an m-valent onium cation. Suitableexamples of the onium cation as M′^(m+) include those exemplified as thecation represented by Formulae (ca-1) to (ca-4).

Among these, a cation represented by Formula (ca-1) is preferable, andspecific examples thereof include cations represented by ChemicalFormulae (ca-1-1) to (ca-1-78) and (ca-1-101) to (ca-1-149).

Among the components (b-1), (b-2), and (b-3), as the onium salt-basedacid generator in the present invention, the component (b-1) isparticularly preferable.

In the resist composition according to the present embodiment, thecomponent (B) may be used alone or in combination of two or more kindsthereof.

In a case where the resist composition contains the component (B), thecontent of the component (B) in the resist composition is preferably 50parts by mass or less, more preferably in a range of 1 to 40 parts bymass, and still more preferably in a range of 5 to 30 parts by mass withrespect to 100 parts by mass of the component (A).

In a case where the content of the component (B) is set to be in theabove-described range, pattern formation can be satisfactorilyperformed.

<<Component (D)>>

The resist composition of the present embodiment may further contain abase component (a “component (D)”) that does not correspond to thecomponent (D0) in addition to the component (A) and the component (D0)or the component (A), the component (D0), and the component (B). Thecomponent (D) functions as a quencher (an acid diffusion control agent)which traps the acid generated in the resist composition upon exposure.

Examples of the component (D) include a nitrogen-containing organiccompound (D1) (hereinafter, the “component (D1)”) and aphotodecomposable base (D2) (hereinafter, referred to as a “component(D2)”) which does not correspond to the component (D1) or the component(D0) and is decomposed upon exposure and then loses the acid diffusioncontrollability.

In a case where a resist composition containing the component (D1) isobtained, the contrast between exposed portions and unexposed portionsof the resist film can be further improved at the time of formation of aresist pattern.

In Regard to Component (D1)

The component (D1) is a base component which is a nitrogen-containingorganic compound component functioning as an acid diffusion controlagent in the resist composition.

The component (D1) is not particularly limited as long as the component(D1) functions as an acid diffusion control agent, and examples thereofinclude an aliphatic amine and an aromatic amine.

Among examples, a secondary aliphatic amine or a tertiary aliphaticamine is preferable as the aliphatic amine.

An aliphatic amine is an amine having one or more aliphatic groups, andthe aliphatic groups preferably have 1 to 12 carbon atoms.

Examples of these aliphatic amines include amines in which at least onehydrogen atom of ammonia (NH₃) has been substituted with an alkyl groupor hydroxyalkyl group having 12 or less carbon atoms (alkylamines oralkylalcoholamines), and cyclic amines.

Specific examples of alkylamines and alkylalcoholamines includemonoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine,n-nonylamine, and n-decylamine; dialkylamines such as diethylamine,di-n-propylamine, di-n-heptylamine, di-n-octylamine, anddicyclohexylamine; trialkylamines such as trimethylamine, triethylamine,tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine,tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine,tri-n-nonylamine, tri-n-decylamine, and tri-n-dodecylamine; and alkylalcohol amines such as diethanolamine, triethanolamine,diisopropanolamine, triisopropanolamine, di-n-octanolamine, andtri-n-octanolamine. Among these, trialkylamines of 5 to 10 carbon atomsare preferable, and tri-n-pentylamine and tri-n-octylamine areparticularly preferable.

Examples of the cyclic amine include heterocyclic compounds containing anitrogen atom as a hetero atom. The heterocyclic compound may be amonocyclic compound (aliphatic monocyclic amine), or a polycycliccompound (aliphatic polycyclic amine).

Specific examples of the aliphatic monocyclic amine include piperidineand piperazine.

The aliphatic polycyclic amine preferably has 6 to 10 carbon atoms, andspecific examples thereof include 1, 5-diazabicyclo[4.3.0]-5-nonene,1,8-diazabicyclo[5.4.0]-7-undecene, hexamethylenetetramine, and1,4-diazabicyclo[2.2.2]octane.

Examples of other aliphatic amines includetris(2-methoxymethoxyethyl)amine, tris {2-(2-methoxyethoxy)ethyl}amine,tris {2-(2-methoxyethoxymethoxy)ethyl}amine, tris{2-(1-methoxyethoxy)ethyl}amine, tris {2-(1-ethoxyethoxy)ethyl}amine,tris {2-(1-ethoxypropoxy)ethyl}amine, tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine and triethanolaminetriacetate, and triethanolamine triacetate is preferable.

Examples of aromatic amines include 4-dimethylaminopyridine, pyrrole,indole, pyrazole, imidazole and derivatives thereof, tribenzylamine, ananiline compound, and N-tert-butoxycarbonylpyrrolidine.

The component (D1) may be used alone or in combination of two or morekinds thereof.

Among the examples, as the component (D1), an aromatic amine ispreferable, and an aniline compound is more preferable. Examples of theaniline compound include 2,6-diisopropylaniline, N,N-dimethylaniline,N,N-dibutylaniline, and N,N-dihexylaniline.

In a case where the resist composition contains the component (D1), thecontent of the component (D1) in the resist composition is typically ina range of 0.01 to 5 parts by mass with respect to 100 parts by mass ofthe component (A). In a case where the content thereof is set to be inthe above-described range, the component (D1) and other components canbe balanced, and various lithography characteristics are improved.

In Regard to Component (D2)

The component (D2) is not particularly limited as long as the componentdoes not correspond to the component (D0) and is decomposed uponexposure and loses the acid diffusion controllability, and one or morecompounds selected from the group consisting of a compound representedby Formula (d2-1) (hereinafter, referred to as a “component (d2-1)”), acompound represented by Formula (d2-2) (hereinafter, referred to as a“component (d2-2)”), and a compound represented by Formula (d2-3)(hereinafter, referred to as a “component (d2-3)”) are preferable.

At exposed portions of the resist film, the components (d2-1) to (d2-3)are decomposed and then lose the acid diffusion controllability(basicity), and therefore the components (d2-1) to (d2-3) cannot act asa quencher, whereas at unexposed portions of the resist film, thecomponents (d2-1) to (d2-3) act as a quencher.

[In the formulae, Rd¹ to Rd⁴ represent a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent, or achain-like alkenyl group which may have a substituent. Here, the carbonatom adjacent to the S atom as Rd² in Formula (d2-2) has no fluorineatom bonded thereto. Yd¹ represents a single bond or a divalent linkinggroup. m represents an integer of 1 or greater, and each M′^(m+)independently represents an m-valent onium cation.]

{Component (d2-1)}

Anion Moiety

In Formula (d2-1), Rd¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and examplesthereof are the same as those described above as R¹⁰¹ in Formula (b-1).

Among these, as the group as Rd¹, an aromatic hydrocarbon group whichmay have a substituent, an aliphatic cyclic group which may have asubstituent and a chain-like alkyl group which may have a substituentare preferable.

Examples of the substituent for these groups include a hydroxyl group,an oxo group, an alkyl group, an aryl group, a fluorine atom, afluorinated alkyl group, a lactone-containing cyclic group representedby any of Formulae (a2-r-1) to (a2-r-7), an ether bond, an ester bond,and a combination thereof. In a case where an ether bond or an esterbond is included as the substituent, the substituent may be bonded viaan alkylene group, and a linking group represented by any of Formulae(y-a1-1) to (y-a1-5) is preferable as the substituent.

Suitable examples of the aromatic hydrocarbon group include a phenylgroup, a naphthyl group, and a polycyclic structure having abicyclooctane skeleton (for example, a polycyclic structure formed of acyclic structure having a bicyclooctane skeleton and a cyclic structureother than the cyclic structure having a bicyclooctane skeleton).

As the aliphatic cyclic group a group in which one or more hydrogenatoms have been removed from a polycycloalkane such as adamantane,norbornane, isobomane, tricyclodecane or tetracyclododecane is morepreferable.

The chain-like alkyl group preferably has 1 to 10 carbon atoms, andspecific examples thereof include a linear alkyl group such as a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a nonyl group, or a decylgroup, and a branched alkyl group such as a 1-methylethyl group, a1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a3-methylpentyl group, or a 4-methylpentyl group.

In a case where the chain-like alkyl group is a fluorinated alkyl grouphaving a fluorine atom or a fluorinated alkyl group as a substituent,the fluorinated alkyl group has preferably 1 to 11 carbon atoms, morepreferably 1 to 8 carbon atoms, and still more preferably 1 to 4 carbonatoms. The fluorinated alkyl group may contain an atom other than afluorine atom. Examples of the atom other than a fluorine atom includean oxygen atom, a sulfur atom, and a nitrogen atom.

As Rd¹, a fluorinated alkyl group in which some or all hydrogen atomsconstituting a linear alkyl group have been substituted with fluorineatom(s) is preferable, and a fluorinated alkyl group in which all of thehydrogen atoms constituting a linear alkyl group have been substitutedwith fluorine atoms (a linear perfluoroalkyl group) is particularlypreferable.

Specific examples of preferable anion moieties for the component (d2-1)are shown below.

Cation Moiety

In Formula (d2-1), M′^(m+) represents an m-valent onium cation.

Suitable examples of the onium cation as M′^(m+) include thoseexemplified as the cation represented by Formulae (ca-1) to (ca-4).Specific examples thereof include cations respectively represented byChemical Formulae (ca-1-1) to (ca-1-78) and (ca-1-101) to (ca-1-149).

The component (d2-1) may be used alone or in combination of two or morekinds thereof.

{Component (d2-2)}

Anion Moiety

In Formula (d2-2), Rd² represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent, or achain-like alkenyl group which may have a substituent, and the samegroups as those described above as R¹⁰¹ in Formula (b-1) areexemplified.

Here, the carbon atom adjacent to the S atom in Rd² has no fluorine atombonded thereto (the carbon atom adjacent to the sulfur atom in Rd² isnot substituted with a fluorine atom). As a result, the anion of thecomponent (d2-2) becomes an appropriately weak acid anion, therebyimproving the quenching ability of the component (D2).

As Rd², a chain-like alkyl group which may have a substituent or analiphatic cyclic group which may have a substituent is preferable. Thechain-like alkyl group has preferably 1 to 10 carbon atoms and morepreferably 3 to 10 carbon atoms. As the aliphatic cyclic group, a groupin which one or more hydrogen atoms have been removed from adamantane,norbornane, isobomane, tricyclodecane, or tetracyclododecane (which mayhave a substituent) and a group in which one or more hydrogen atoms havebeen removed from camphor are more preferable.

The hydrocarbon group as Rd² may have a substituent. As the substituent,the same groups as the substituents which may be included in thehydrocarbon group (such as an aromatic hydrocarbon group, an aliphaticcyclic group, or a chain-like alkyl group) as Rd¹ in Formula (d2-1) canbe exemplified.

Specific examples of preferable anion moieties for the component (d2-2)are shown below.

Cation Moiety

In Formula (d2-2), M′^(m+) represents an m-valent onium cation and hasthe same definition as that for M′^(m+) in Formula (d2-1).

The component (d2-2) may be used alone or in combination of two or morekinds thereof.

{Component (d2-3)}

Anion Moiety

In Formula (d2-3), Rd³ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent, or achain-like alkenyl group which may have a substituent, and the samegroups as those described above as R¹⁰¹ in Formula (b-1) areexemplified, and a cyclic group containing a fluorine atom, a chain-likealkyl group, or a chain-like alkenyl group is preferable. Among these, afluorinated alkyl group is preferable, and the same fluorinated alkylgroups as those described above as Rd¹ are more preferable.

In Formula (d2-3), Rd⁴ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and the samegroups as those described above as R¹⁰¹ in Formula (b-1) areexemplified.

Among these, an alkyl group which may have substituent, an alkoxy groupwhich may have substituent, an alkenyl group which may have substituent,or a cyclic group which may have substituent is preferable.

The alkyl group as Rd⁴ is preferably a linear or branched alkyl grouphaving 1 to 5 carbon atoms, and specific examples thereof include amethyl group, an ethyl group, a propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, anisopentyl group, and a neopentyl group. Some hydrogen atoms in the alkylgroup as Rd⁴ may be substituted with a hydroxyl group, a cyano group, orthe like.

The alkoxy group as Rd⁴ is preferably an alkoxy group having 1 to 5carbon atoms, and specific examples thereof include a methoxy group, anethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxygroup, and a tert-butoxy group. Among these, a methoxy group and anethoxy group are preferable.

As the alkenyl group as Rd⁴, the same groups as those described above asR¹⁰¹ in Formula (b-1) can be exemplified, and a vinyl group, a propenylgroup (an allyl group), a 1-methylpropenyl group, and a 2-methylpropenylgroup are preferable. These groups may have an alkyl group having 1 to 5carbon atoms or a halogenated alkyl group having 1 to 5 carbon atoms asa substituent.

As the cyclic group as Rd⁴, the same groups as those described above asR¹⁰¹ in Formula (b-1) can be exemplified. Among these, as the cyclicgroup, an alicyclic group in which one or more hydrogen atoms have beenremoved from a cycloalkane such as cyclopentane, cyclohexane,adamantane, norbomane, isobomane, tricyclodecane or tetracyclododecaneor an aromatic group such as a phenyl group or a naphthyl group ispreferable. In a case where Rd⁴ represents an alicyclic group, theresist composition can be satisfactorily dissolved in an organicsolvent, thereby improving the lithography characteristics.

In Formula (d2-3), Yd¹ represents a single bond or a divalent linkinggroup.

The divalent linking group as Yd¹ is not particularly limited, andexamples thereof include a divalent hydrocarbon group (an aliphatichydrocarbon group or an aromatic hydrocarbon group) which may have asubstituent and a divalent linking group containing a hetero atom. Thedivalent linking groups are the same as described above as the divalenthydrocarbon group which may have a substituent and the divalent linkinggroup containing a hetero atom explained above as the divalent linkinggroup as Ya^(x1) in Formula (a10-1).

As Yd¹, a carbonyl group, an ester bond, an amide bond, an alkylenegroup, or a combination of these is preferable. As the alkylene group, alinear or branched alkylene group is more preferable, and a methylenegroup or an ethylene group is still more preferable.

Specific examples of preferable anion moieties for the component (d2-3)are shown below.

Cation Moiety

In Formula (d2-3), M′^(m+) represents an m-valent onium cation and hasthe same definition as that for M′^(m+) in Formula (d2-1).

The component (d2-3) may be used alone or in combination of two or morekinds thereof.

As the component (D2), only one of the above-described components (d2-1)to (d2-3) or a combination of two or more kinds thereof may be used.

In a case where the resist composition contains the component (D2), thecontent of the component (D2) in the resist composition is preferably ina range of 0.5 to 35 parts by mass, more preferably in a range of 1 to25 parts by mass, still more preferably in a range of 2 to 20 parts bymass, and particularly preferably in a range of 3 to 15 parts by masswith respect to 100 parts by mass of the component (A).

In a case where the content of the component (D2) is greater than orequal to the preferable lower limit, excellent lithographycharacteristics and an excellent resist pattern shape are easilyobtained. Further, in a case where the content thereof is less than orequal to the upper limit thereof, the component (D2) and othercomponents can be balanced, and various lithography characteristics areimproved.

Method of Producing Component (D2):

The production methods of the components (d2-1) and (d2-2) are notparticularly limited, and the components (d2-1) and (d2-2) can beproduced by known methods.

Further, the method of producing the component (d2-3) is notparticularly limited, and the component (d2-3) can be produced in thesame manner as disclosed in United States Patent Application,Publication No. 2012-0149916.

Among the examples, as the component (D) in the resist compositionaccording to the present embodiment, the component (D2) is preferable,and the component (d2-1) is more preferable.

<<Component (E): At Least One Compound (E) Selected from GroupConsisting of Organic Carboxylic Acids, Phosphorus Oxo Acids, andDerivatives Thereof>>

For the purpose of preventing any deterioration in sensitivity, andimproving the resist pattern shape and the post exposure temporalstability, the resist composition of the present embodiment may containat least one compound (E) (hereinafter referred to as the component (E))selected from the group consisting of an organic carboxylic acid, or aphosphorus oxo acid and a derivative thereof.

Examples of suitable organic carboxylic acids include acetic acid,malonic acid, citric acid, malic acid, succinic acid, benzoic acid, andsalicylic acid.

Examples of phosphorus oxo acids include phosphoric acid, phosphonicacid, and phosphinic acid. Among these, phosphonic acid is particularlypreferable.

Examples of phosphorus oxo acid derivatives include esters in which ahydrogen atom in the above-described oxo acids is substituted with ahydrocarbon group.

Examples of the hydrocarbon group include an alkyl group having 1 to 5carbon atoms and an aryl group having 6 to 15 carbon atoms.

Examples of phosphoric acid derivatives include phosphoric acid esterssuch as di-n-butyl phosphate and diphenyl phosphate.

Examples of phosphonic acid derivatives include phosphonic acid esterssuch as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonicacid, diphenyl phosphonate, and dibenzyl phosphonate.

Examples of phosphinic acid derivatives include phosphinic acid estersand phenylphosphinic acid.

In the resist composition of the present embodiment, the component (E)may be used alone or in combination of two or more kinds thereof.

In a case where the resist composition contains the component (E), thecontent of the component (E) is typically in a range of 0.01 to 5 partsby mass, with respect to 100 parts by mass of the component (A).

<<Component (F): Fluorine Additive Component>>

In the present embodiment, the resist composition may further include afluorine additive (hereinafter, referred to as a “component (F)”) inorder to impart water repellency to the resist film or to improve thelithography characteristics.

As the component (F), a fluorine-containing polymer compound describedin Japanese Unexamined Patent Application, First Publication No.2010-002870, Japanese Unexamined Patent Application, First PublicationNo. 2010-032994, Japanese Unexamined Patent Application, FirstPublication No. 2010-277043, Japanese Unexamined Patent Application,First Publication No. 2011-13569, and Japanese Unexamined PatentApplication, First Publication No. 2011-128226 can be exemplified.

Specific examples of the component (F) include polymers having aconstitutional unit (f1) represented by Formula (f1-1) shown below. Asthe polymer, a polymer (homopolymer) consisting of a constitutional unit(f1) represented by Formula (f1-1) shown below; a copolymer of theconstitutional unit (f1) and the above-described constitutional unit(a4); a copolymer of the constitutional unit (f1) and theabove-described constitutional unit (a1); and a copolymer of theconstitutional unit (f1), a constitutional unit derived from acrylicacid or methacrylic acid, and the above-described constitutional unit(a1) are preferable. Preferred examples of the constitutional unit (a1)to be copolymerized with the constitutional unit (f1) include aconstitutional unit derived from 1-ethyl-1-cyclooctyl (meth)acrylate anda constitutional unit derived from 1-methyl-1-adamantyl (meth)acrylate.

[In the formula, R has the same definition as described above. Rf¹⁰² andRf¹⁰³ each independently represent a hydrogen atom, a halogen atom, analkyl group having 1 to 5 carbon atoms, or a halogenated alkyl grouphaving 1 to 5 carbon atoms, and Rf¹⁰² and Rf¹⁰³ may be the same as ordifferent from each other. nf¹ represents an integer of 0 to 5. Rf¹⁰¹represents an organic group containing a fluorine atom.]

In Formula (f1-1), R bonded to the carbon atom at the α-position has thesame definition as described above. As R, a hydrogen atom or a methylgroup is preferable.

In Formula (f1-1), examples of the halogen atom as Rf¹⁰² and Rf¹⁰³include a fluorine atom, a chlorine atom, a bromine atom, and an iodineatom, and a fluorine atom is particularly preferable. Examples of thealkyl group having 1 to 5 carbon atoms as Rf¹⁰² and Rf¹⁰³ include thosedescribed above as the alkyl group having 1 to 5 carbon atoms as R, anda methyl group or an ethyl group is preferable. Specific examples of thehalogenated alkyl group having 1 to 5 carbon atoms as Rf¹⁰² and Rf¹⁰³include groups in which some or all hydrogen atoms of theabove-described alkyl groups of 1 to 5 carbon atoms have beensubstituted with halogen atoms.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom, and an iodine atom, and a fluorine atom is particularlypreferable. Among these examples, as Rf¹⁰² and Rf¹⁰³, a hydrogen atom, afluorine atom, or an alkyl group having 1 to 5 carbon atoms ispreferable, and a hydrogen atom, a fluorine atom, a methyl group, or anethyl group is more preferable.

In Formula (f1-1), nf¹ represents an integer of 0 to 5, preferably aninteger of 0 to 3, and more preferably an integer of 0 or 1.

In Formula (f1-1), Rf¹⁰¹ represents an organic group containing afluorine atom, and is preferably a hydrocarbon group containing afluorine atom.

The hydrocarbon group containing a fluorine atom may be linear,branched, or cyclic, and has preferably 1 to 20 carbon atoms, morepreferably 1 to 15 carbon atoms, and particularly preferably 1 to 10carbon atoms.

Among these, as Rf¹⁰¹, a fluorinated hydrocarbon group having 1 to 6carbon atoms is more preferable, and a trifluoromethyl group, —CH₂—CF₃,—CH₂—CF₂—CF₃, —CH(CF₃)₂, —CH₂—CH₂—CF₃, and —CH₂—CH₂—CF₂—CF₂—CF₂—CF₃ arestill more preferable.

The weight-average molecular weight (Mw) (in terms of polystyrenedetermined by gel permeation chromatography) of the component (F) ispreferably in a range of 1000 to 50000, more preferably in a range of5000 to 40000, and most preferably in a range of 10000 to 30000. In acase where the weight-average molecular weight is less than or equal tothe upper limit of the above-described range, the resist compositionexhibits a satisfactory solubility in a solvent for a resist enough tobe used as a resist. On the other hand, in a case where theweight-average molecular weight is greater than or equal to the lowerlimit of the above-described range, dry etching resistance and thecross-sectional shape of the resist pattern become excellent.

Further, the dispersity (Mw/Mn) of the component (F) is preferably in arange of 1.0 to 5.0, more preferably in a range of 1.0 to 3.0, and mostpreferably in a range of 1.2 to 2.5.

In the resist composition of the present embodiment, the component (F)may be used alone or in combination of two or more kinds thereof.

In a case where the resist composition contains the component (F), thecontent of the component (F) is typically in a range of 0.5 to 10 partsby mass, with respect to 100 parts by mass of the component (A).

<<Component (S): Organic Solvent Component>>

The resist composition of the present embodiment may be produced bydissolving the resist materials in an organic solvent (hereinafter,referred to as a “component (S)”).

The component (S) may be any organic solvent which can dissolve therespective components to be used to obtain a uniform solution, andoptional organic solvent can be appropriately selected from those whichhave been conventionally known as solvents for a chemically amplifiedresist composition and then used.

Examples thereof include lactones such as γ-butyrolactone; ketones suchas acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentyl ketone,methyl isopentyl ketone, 2-heptanone, ethylene carbonate, and propylenecarbonate; polyhydric alcohols, such as ethylene glycol, diethyleneglycol, propylene glycol and dipropylene glycol; compounds having anester bond, such as ethylene glycol monoacetate, diethylene glycolmonoacetate, propylene glycol monoacetate, and dipropylene glycolmonoacetate; polyhydric alcohol derivatives including compounds havingan ether bond, such as a monoalkylether (such as monomethylether,monoethylether, monopropylether or monobutylether) or monophenylether ofany of these polyhydric alcohols or compounds having an ester bond(among these, propylene glycol monomethyl ether acetate (PGMEA) andpropylene glycol monomethyl ether (PGME) are preferable); cyclic etherssuch as dioxane; esters such as methyl lactate, ethyl lactate (EL),methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethylpyruvate, methyl methoxypropionate, and ethyl ethoxypropionate; aromaticorganic solvents such as anisole, ethylbenzylether, cresylmethylether,diphenylether, dibenzylether, phenetole, butylphenylether, ethylbenzene,diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymeneand mesitylene; and dimethylsulfoxide (DMSO).

In the resist composition of the present embodiment, the component (S)may be used alone or in the form of a mixed solvent of two or more kindsthereof.

Among these, PGMEA, PGME, γ-butyrolactone, propylene carbonate, EL, andcyclohexanone are preferable.

Further, a mixed solvent obtained by mixing PGMEA with a polar solventis also preferable. The blending ratio (mass ratio) of the mixed solventcan be appropriately determined, taking into consideration thecompatibility of the PGMEA with the polar solvent, but is preferably inthe range of 1:9 to 9:1 and more preferably in a range of 2:8 to 8:2.

More specifically, in a case where EL or cyclohexanone is blended as thepolar solvent, the PGMEA:EL or cyclohexanone mass ratio is preferably ina range of 1:9 to 9:1 and more preferably in a range of 2:8 to 8:2.Alternatively, in a case where PGME is blended as the polar solvent, thePGMEA:PGME mass ratio is preferably in a range of 1:9 to 9:1, morepreferably in a range of 2:8 to 8:2, and still more preferably in arange of 3:7 to 7:3. Furthermore, a mixed solvent of PGMEA, PGME andcyclohexanone is also preferable.

Further, as the component (S), a mixed solvent of at least one selectedfrom PGMEA and EL and at least one selected from γ-butyrolactone andpropylene carbonate is also preferable. In this case, as the mixingratio, the mass ratio between the former and the latter is preferably ina range of 60:40 to 99:1 and more preferably in a range of 70:30 to95:5.

The amount of the component (S) is not particularly limited and isappropriately set to have a concentration which enables coating of acoating solution to a substrate or the like depending on the thicknessof the coated film. In general, the component (S) is used in an amountsuch that the solid content of the resist composition becomes in therange of 0.1% to 20% by mass and preferably in a range of 0.2% to 15% bymass.

Impurities or the like may be removed from the resist composition of thepresent embodiment using a polyimide porous film, a polyamideimideporous film, or the like after the resist material is dissolved in thecomponent (S). For example, the resist composition may be filtered usinga filter formed of a polyimide porous film, a filter formed of apolyamideimide porous film, or a filter formed of a polyimide porousfilm and a polyamideimide porous film. Examples of the polyimide porousfilm and the polyamideimide porous film include those described inJapanese Unexamined Patent Application, First Publication No.2016-155121.

As desired, other miscible additives can also be added to the resistcomposition of the present embodiment. The resist composition maycontain miscible additives such as additive resins, dissolutioninhibitors, plasticizers, stabilizers, colorants, halation preventionagents, and dyes for improving the performance of the resist film, asappropriate.

The resist composition according to the present embodiment contains thecomponent (A), the component (D0), and optional components as necessary.

Suitable examples thereof include a resist composition containing thecomponent (A), the component (D0), and the component (B).

The above-described resist composition according to the presentembodiment contains the resin component (A1) having the constitutionalunit (a0) and the constitutional unit (a1), and the component (D0).Since the constitutional unit (a0) contains an aromatic ring hydroxygroup serving as a proton source, the sensitivity can be improved due toan increase in amount of the acid to be generated. Further, since theanion moiety contains a plurality of aromatic ring hydroxy groups alsoin a case of the component (D0), the ability of the proton source isincreased, and the solubility in a developing solution is increased.Therefore, the sensitivity can be further improved.

In addition, the solubility of an exposed portion in a developingsolution is improved because the component (D0) has an anion moiety, andthus the contrast between an exposed portion and an unexposed portion isincreased. Therefore, it is assumed that in a case where the resincomponent (A1) having the constitutional unit (a1) and theconstitutional unit (D0) and the component (D0) are used in combination,improvement of the sensitivity and the resolution and reduction inroughness can be achieved at the time of formation of the resistpattern.

(Method of Forming a Resist Pattern)

The method of forming a resist pattern according to the second aspect ofthe present invention includes a step of forming a resist film on asupport using the resist composition of the embodiment; a step ofexposing the resist film; and a step of developing the exposed resistfilm to form a resist pattern.

According to the embodiment of the method of forming a resist pattern, amethod of forming a resist pattern by performing processes as describedbelow is exemplified.

First, a resist composition of the according to the embodiment isapplied to a support using a spinner or the like, and a bake treatment(post applied bake (PAB)) is conducted at a temperature of 80 to 150° C.for 40 to 120 seconds and preferably 60 to 90 seconds, to form a resistfilm.

Following selective exposure of the thus formed resist film, by exposurethrough a mask having a predetermined pattern formed thereon (maskpattern) using an immersion exposure apparatus such as an electron beamlithography apparatus or an EUV immersion exposure apparatus, or bypatterning via direct irradiation with an electron beam without using amask pattern, baking treatment (post exposure baking (PEB)) is conductedunder temperature conditions of 80 to 150° C. for 40 to 120 seconds, andpreferably 60 to 90 seconds.

Next, the resist film is subjected to a developing treatment. Thedeveloping treatment is conducted using an alkali developing solution ina case of an alkali developing process, and a developing solutioncontaining an organic solvent (organic developing solution) in a case ofa solvent developing process.

After the developing treatment, it is preferable to conduct a rinsetreatment. As the rinse treatment, water rinsing using pure water ispreferable in a case of an alkali developing process, and rinsing usinga rinse solution containing an organic solvent is preferable in a caseof a solvent developing process.

In a case of a solvent developing process, after the developingtreatment or the rinsing, the developing solution or the rinse liquidremaining on the pattern can be removed by a treatment using asupercritical fluid.

After the developing treatment or the rinse treatment, drying isconducted. As desired, bake treatment (post bake) can be conductedfollowing the developing treatment.

In this manner, a resist pattern can be formed.

The support is not specifically limited and a conventionally knownsupport can be used. For example, substrates for electronic components,and such substrates having wiring patterns formed thereon can be used.Specific examples of the material of the substrate include metals suchas silicon wafer, copper, chromium, iron and aluminum; and glass.Suitable materials for the wiring pattern include copper, aluminum,nickel, and gold.

Further, as the support, any one of the above-described supportsprovided with an inorganic and/or organic film on the surface thereofmay be used. As the inorganic film, an inorganic antireflection film(inorganic BARC) can be used. As the organic film, an organicantireflection film (organic BARC) and an organic film such as alower-layer organic film used in a multilayer resist method can be used.

Here, a multilayer resist method is method in which at least one layerof an organic film (lower-layer organic film) and at least one layer ofa resist film (upper-layer resist film) are provided on a substrate, anda resist pattern formed on the upper-layer resist film is used as a maskto conduct patterning of the lower-layer organic film. This method isconsidered as being capable of forming a pattern with a high aspectratio. More specifically, in the multilayer resist method, a desiredthickness can be ensured by the lower-layer organic film, and as aresult, the thickness of the resist film can be reduced, and anextremely fine pattern with a high aspect ratio can be formed.

The multilayer resist method is classified into a method in which adouble-layer structure consisting of an upper-layer resist film and alower-layer organic film is formed (double-layer resist method), and amethod in which a multilayer structure having at least three layersconsisting of an upper-layer resist film, a lower-layer organic film andat least one intermediate layer (thin metal film or the like) providedbetween the upper-layer resist film and the lower-layer organic film(triple-layer resist method).

The wavelength to be used for exposure is not particularly limited andthe exposure can be conducted using radiation such as an ArF excimerlaser, a KrF excimer laser, an F₂ excimer laser, extreme ultravioletrays (EUV), vacuum ultraviolet rays (VUV), electron beams (EB), X-rays,and soft X-rays. The resist composition is useful for a KrF excimerlaser, an ArF excimer laser, EB, and EUV, more useful for an ArF excimerlaser, EB, and EUV, and particularly useful for EB and EUV. In otherwords, the method of forming a resist pattern according to the presentembodiment is a method particularly useful in a case where the step ofexposing the resist film includes a process of exposing the resist filmto extreme ultraviolet rays (EUV) or electron beams (EB).

The exposure of the resist film can be a general exposure (dry exposure)conducted in air or an inert gas such as nitrogen, or liquid immersionexposure (liquid immersion lithography).

In liquid immersion lithography, the region between the resist film andthe lens at the lowermost point of the immersion exposure apparatus ispre-filled with a solvent (liquid immersion medium) that has a largerrefractive index than the refractive index of air, and the exposure(immersion exposure) is conducted in this state.

As the liquid immersion medium, a solvent which exhibits a refractiveindex larger than the refractive index of air but smaller than therefractive index of the resist film to be exposed is preferable. Therefractive index of the immersion medium is not particularly limited aslong as it satisfies the above-described requirements.

Examples of this solvent which exhibits a refractive index that islarger than the refractive index of air but smaller than the refractiveindex of the resist film include water, fluorine-based inert liquids,silicon-based solvents, and hydrocarbon-based solvents.

Specific examples of the fluorine-based inert liquids include liquidscontaining a fluorine-based compound such as C₃HCl₂F₅, C₄F₉OCH₃,C₄F₉OC₂H₅ or C₅H₃F₇ as the main component, and the boiling point ispreferably in a range of 70° C. to 180° C. and more preferably in arange of 80° C. to 160° C. A fluorine-based inert liquid having aboiling point in the above-described range is advantageous in that theremoval of the immersion medium after the exposure can be conducted by asimple method.

As a fluorine-based inert liquid, a perfluoroalkyl compound in which allof the hydrogen atoms of the alkyl group are substituted with fluorineatoms is particularly preferable. Examples of these perfluoroalkylcompounds include perfluoroalkylether compounds and perfluoroalkylaminecompounds.

Specifically, an example of a suitable perfluoroalkylether compound isperfluoro(2-butyl-tetrahydrofuran) (boiling point of 102° C.), and anexample of a suitable perfluoroalkylamine compound isperfluorotributylamine (boiling point of 174° C.).

As the immersion medium, water is preferable in terms of cost, safety,environment and versatility.

As an example of the alkali developing solution used in an alkalideveloping process, a 0.1 to 10% by mass aqueous solution oftetramethylammonium hydroxide (TMAH) can be exemplified.

As the organic solvent contained in the organic developing solution usedfor a developing treatment in a solvent developing process, any of theconventional organic solvents can be used which are capable ofdissolving the component (A) (prior to exposure). Specific examples ofthe organic solvent include polar solvents such as ketone solvents,ester solvents, alcohol solvents, nitrile solvents, amide solvents andether solvents, and hydrocarbon solvents.

A ketone solvent is an organic solvent containing C—C(═O)—C in thestructure thereof. An ester solvent is an organic solvent containingC—C(═O)—O—C in the structure thereof. An alcohol solvent is an organicsolvent containing an alcoholic hydroxyl group in the structure thereof.An “alcoholic hydroxyl group” indicates a hydroxyl group bonded to acarbon atom of an aliphatic hydrocarbon group. A nitrile solvent is anorganic solvent containing a nitrile group in the structure thereof. Anamide solvent is an organic solvent containing an amide group in thestructure thereof. An ether solvent is an organic solvent containingC—O—C in the structure thereof.

Some organic solvents have a plurality of the functional groups whichcharacterizes the above-described solvents in the structure thereof. Insuch a case, the organic solvent can be classified as any type of thesolvent having the characteristic functional group. For example,diethylene glycol monomethylether can be classified as an alcoholsolvent or an ether solvent.

A hydrocarbon solvent consists of a hydrocarbon which may behalogenated, and does not have any substituent other than a halogenatom. Examples of the halogen atom include a fluorine atom, a chlorineatom, a bromine atom and an iodine atom, and a fluorine atom ispreferable.

As the organic solvent contained in the organic developing solution,among these, a polar solvent is preferable, and ketone solvents, estersolvents, and nitrile solvents are preferable.

Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone,2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutylketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethylketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone,diacetonylalcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone,isophorone, propylenecarbonate, γ-butyrolactone and methyl amyl ketone(2-heptanone). Among these examples, as a ketone solvent, methyl amylketone (2-heptanone) is preferable.

Examples of ester solvents include methyl acetate, butyl acetate, ethylacetate, isopropyl acetate, amyl acetate, isoamyl acetate, ethylmethoxyacetate, ethyl ethoxyacetate, ethylene glycol monoethyl etheracetate, ethylene glycol monopropyl ether acetate, ethylene glycolmonobutyl ether acetate, ethylene glycol monophenyl ether acetate,diethylene glycol monomethyl ether acetate, diethylene glycol monopropylether acetate, diethylene glycol monophenyl ether acetate, diethyleneglycol monobutyl ether acetate, diethylene glycol monoethyl etheracetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate, 4-methoxybutylacetate, 3-methyl-3-methoxybutyl acetate, 3-ethyl-3-methoxybutylacetate, propylene glycol monomethyl ether acetate, propylene glycolmonoethyl ether acetate, propylene glycol monopropyl ether acetate,2-ethoxybutyl acetate, 4-ethoxybutyl acetate, 4-propoxybutyl acetate,2-methoxypentyl acetate, 3-methoxypentyl acetate, 4-methoxypentylacetate, 2-methyl-3-methoxypentyl acetate, 3-methyl-3-methoxypentylacetate, 3-methyl-4-methoxypentyl acetate, 4-methyl-4-methoxypentylacetate, propylene glycol diacetate, methyl formate, ethyl formate,butyl formate, propyl formate, ethyl lactate, butyl lactate, propyllactate, ethyl carbonate, propyl carbonate, butyl carbonate, methylpyruvate, ethyl pyruvate, propyl pyruvate, butyl pyruvate, methylacetoacetate, ethyl acetoacetate, methyl propionate, ethyl propionate,propyl propionate, isopropyl propionate, methyl 2-hydroxypropionate,ethyl 2-hydroxypropionate, methyl-3-methoxypropionate,ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate, andpropyl-3-methoxypropionate. Among these examples, as an ester solvent,butyl acetate is preferable.

Examples of nitrile solvents include acetonitrile, propionitrile,valeronitrile, butyronitrile and the like.

As desired, the organic developing solution may have a conventionaladditive blended. Examples of the additive include surfactants. Thesurfactant is not particularly limited, and for example, an ionic ornon-ionic fluorine and/or silicon surfactant can be used.

As the surfactant, a non-ionic surfactant is preferable, and a non-ionicfluorine surfactant or a non-ionic silicon surfactant is morepreferable.

In a case where a surfactant is blended, the amount of the surfactant tobe blended is typically 0.001% to 5% by mass, preferably 0.005% to 2% bymass, and more preferably 0.01% to 0.5% by mass with respect to thetotal amount of the organic developing solution.

The developing treatment can be performed by a conventional developingmethod. Examples thereof include a method in which the substrate isimmersed in the developing solution for a predetermined time (a dipmethod), a method in which the developing solution is cast up on thesurface of the support by surface tension and maintained for apredetermined period (a puddle method), a method in which the developingsolution is sprayed onto the surface of the support (spray method), anda method in which the developing solution is continuously ejected from adeveloping solution ejecting nozzle while scanning at a constant rate toapply the developing solution to the support while rotating thesubstrate at a constant rate (dynamic dispense method).

As the organic solvent contained in the rinse liquid used in the rinsetreatment after the developing treatment in a case of a solventdeveloping process, any of the above-described organic solventscontained in the organic developing solution can be used which hardlydissolves the resist pattern. In general, at least one solvent selectedfrom the group consisting of hydrocarbon solvents, ketone solvents,ester solvents, alcohol solvents, amide solvents and ether solvents isused. Among these, at least one solvent selected from the groupconsisting of hydrocarbon solvents, ketone solvents, ester solvents,alcohol solvents and amide solvents is preferable, more preferably atleast one solvent selected from the group consisting of alcohol solventsand ester solvents, and an alcohol solvent is particularly preferable.

The alcohol solvent used for the rinse liquid is preferably a monohydricalcohol of 6 to 8 carbon atoms, and the monohydric alcohol may belinear, branched or cyclic. Specific examples thereof include 1-hexanol,1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol,3-heptanol, 3-octanol, 4-octanol, and benzyl alcohol. Among these,1-hexanol, 2-heptanol and 2-hexanol are preferable, and 1-hexanol and2-hexanol are more preferable.

As the organic solvent, one kind of solvent may be used alone, or two ormore kinds of solvents may be used in combination. Further, an organicsolvent other than the above-described examples or water may be mixedtogether. However, in consideration of the development characteristics,the amount of water to be blended in the rinse liquid is preferably 30%by mass or less, more preferably 10% by mass or less, still morepreferably 5% by mass or less, and most preferably 3% by mass or lesswith respect to the total amount of the rinse liquid.

A known additive can be blended with the rinse solution as necessary.Examples of the additive include surfactants. As the surfactant, thesame surfactants as those described above can be exemplified, anon-ionic surfactant is preferable, and a non-ionic fluorine surfactantor a non-ionic silicon surfactant is more preferable.

In a case where a surfactant is blended, the amount of the surfactant tobe blended is typically 0.001% to 5% by mass, preferably 0.005% to 2% bymass, and more preferably 0.01% to 0.5% by mass with respect to thetotal amount of the rinse liquid.

The rinse treatment using a rinse liquid (washing treatment) can beconducted by a conventional rinse method. Examples of the rinse methodinclude a method in which the rinse liquid is continuously applied tothe support while rotating it at a constant rate (rotational coatingmethod), a method in which the support is immersed in the rinse liquidfor a predetermined time (dip method), and a method in which the rinseliquid is sprayed onto the surface of the support (spray method).

In the method of forming a resist pattern according to the presentembodiment, since the resist composition according to the firstembodiment is used, a resist pattern with excellent lithographycharacteristics (the sensitivity, reduction in roughness, theresolution, and the like) can be formed during formation of the resistpattern.

EXAMPLES

Hereinafter, the present invention will be described in more detailbased on examples, but the present invention is not limited to theseexamples.

<Preparation of Resist Composition>

Examples 1 to 9 and Comparative Examples 1 to 5

Respective components listed in Tables 1 and 2 were mixed and dissolvedto prepare each resist composition of each example.

TABLE 1 Component (A) Component (D) Component Component ComponentComponent Component Component (A1) (A2) (B) (D0) (D2) (S) Example 1(A1)-1 — (B1)-1 (DO)-1 — (S)-1 [100] [15.0] [5.0] [6000] Example 2(A1)-2 — (B1)-1 (DO)-1 — (S)-1 [100] [15.0] [5.0] [6000] Example 3(A1)-3 — (B1)-1 (DO)-1 — (S)-1 [100] [15.0] [5.0] [6000] Example 4(A1)-4 — (B1)-1 (DO)-1 — (S)-1 [100] [15.0] [5.0] [6000] Example 5(A1)-5 — (B1)-1 (DO)-1 — (S)-1 [100] [15.0] [5.0] [6000] Example 6(A1)-6 — (B1)-1 (DO)-1 — (S)-1 [100] [15.0] [5.0] [6000] Example 7(A1)-7 — (B1)-1 (DO)-1 — (S)-1 [100] [15.0] [5.0] [6000] Example 8(A1)-2 — (B1)-1 (DO)-2 — (S)-1 [100] [15.0] [5.0] [6000] Example 9(A1)-2 — (B1)-1 (DO)-3 — (S)-1 [100] [15.0] [5.0] [6000]

TABLE 2 Component (A) Component (D) Component Component ComponentComponent Component Component (A1) (A2) (B) (D0) (D2) (S) Comparative —(A2)-1 (B1)-1 (DO)-1 — (S)-1 Example 1 [100] [15.0] [5.0] [6000]Comparative — (A2)-2 (B1)-1 (DO)-1 — (S)-1 Example 2 [100] [15.0] [5.0][6000] Comparative (A1)-2 — (B1)-1 — (D2)-1 (S)-1 Example 3 [100] [15.0][5.0] [6000] Comparative (A1)-2 — (B1)-1 — (D2)-2 (S)-1 Example 4 [100][15.0] [5.0] [6000] Comparative (A1)-2 — (B1)-1 — (D2)-3 (S)-1 Example 5[100] [15.0] [5.0] [6000]

In Tables 1 and 2, each abbreviation has the following meaning. Thenumerical values in the parentheses are blending amounts (parts bymass).

(A1)-1: A polymer compound represented by Chemical Formula (A1-1). Thepolymer compound (A1-1) was obtained by radically polymerizing amonomer, from which a constitutional unit constituting the polymercompound was derived, using a predetermined molar ratio. Theweight-average molecular weight (Mw) of the polymer compound (A1-1) andthe molecular weight dispersity (Mw/Mn) in terms of standard polystyreneacquired by GPC measurement were respectively 6800 and 1.67. Thecopolymer compositional ratio (the proportion (molar ratio) betweenconstitutional units (1/m) in the structural formula) acquired by¹³C-NMR was 50/50.

(A1)-2: A polymer compound represented by Chemical Formula (A1-2). Thepolymer compound (A1-2) was obtained by radically polymerizing amonomer, from which a constitutional unit constituting the polymercompound was derived, using a predetermined molar ratio. Theweight-average molecular weight (Mw) of the polymer compound (A1-2) andthe molecular weight dispersity (Mw/Mn) in terms of standard polystyreneacquired by GPC measurement were respectively 7000 and 1.70. Thecopolymer compositional ratio (the proportion (molar ratio) betweenconstitutional units (1/m) in the structural formula) acquired by¹³C-NMR was 50/50.

(A1)-3: A polymer compound represented by Chemical Formula (A1-3). Thepolymer compound (A1-3) was obtained by radically polymerizing amonomer, from which a constitutional unit constituting the polymercompound was derived, using a predetermined molar ratio. Theweight-average molecular weight (Mw) of the polymer compound (A1-3) andthe molecular weight dispersity (Mw/Mn) in terms of standard polystyreneacquired by GPC measurement were respectively 6900 and 1.71. Thecopolymer compositional ratio (the proportion (molar ratio) betweenconstitutional units (1/m) in the structural formula) acquired by¹³C-NMR was 50/50.

(A1)-4: A polymer compound represented by Chemical Formula (A1-4). Thepolymer compound (A1-4) was obtained by radically polymerizing amonomer, from which a constitutional unit constituting the polymercompound was derived, using a predetermined molar ratio. Theweight-average molecular weight (Mw) of the polymer compound (A1-4) andthe molecular weight dispersity (Mw/Mn) in terms of standard polystyreneacquired by GPC measurement were respectively 6800 and 1.66. Thecopolymer compositional ratio (the proportion (molar ratio) betweenconstitutional units (1/m) in the structural formula) acquired by¹³C-NMR was 50/50.

(A1)-5: A polymer compound represented by Chemical Formula (A1-5). Thepolymer compound (A1-5) was obtained by radically polymerizing amonomer, from which a constitutional unit constituting the polymercompound was derived, using a predetermined molar ratio. Theweight-average molecular weight (Mw) of the polymer compound (A1-5) andthe molecular weight dispersity (Mw/Mn) in terms of standard polystyreneacquired by GPC measurement were respectively 6900 and 1.69. Thecopolymer compositional ratio (the proportion (molar ratio) betweenconstitutional units (1/m/n) in the structural formula) acquired by¹³C-NMR was 40/50/10.

(A1)-6: A polymer compound represented by Chemical Formula (A1-6). Thepolymer compound (A1-6) was obtained by radically polymerizing amonomer, from which a constitutional unit constituting the polymercompound was derived, using a predetermined molar ratio. Theweight-average molecular weight (Mw) of the polymer compound (A1-6) andthe molecular weight dispersity (Mw/Mn) in terms of standard polystyreneacquired by GPC measurement were respectively 7100 and 1.67. Thecopolymer compositional ratio (the proportion (molar ratio) betweenconstitutional units (1/m/n) in the structural formula) acquired by¹³C-NMR was 40/50/10.

(A1)-7: A polymer compound represented by Chemical Formula (A1-7). Thepolymer compound (A1-7) was obtained by radically polymerizing amonomer, from which a constitutional unit constituting the polymercompound was derived, using a predetermined molar ratio. Theweight-average molecular weight (Mw) of the polymer compound (A1-7) andthe molecular weight dispersity (Mw/Mn) in terms of standard polystyreneacquired by GPC measurement were respectively 7000 and 1.68. Thecopolymer compositional ratio (the proportion (molar ratio) betweenconstitutional units (1/m/n) in the structural formula) acquired by¹³C-NMR was 40/50/10.

(A2)-1: A polymer compound represented by Chemical Formula (A2-1). Thepolymer compound (A2-1) was obtained by radically polymerizing amonomer, from which a constitutional unit constituting the polymercompound was derived, using a predetermined molar ratio. Theweight-average molecular weight (Mw) of the polymer compound (A2-1) andthe molecular weight dispersity (Mw/Mn) in terms of standard polystyreneacquired by GPC measurement were respectively 6900 and 1.66. Thecopolymer compositional ratio (the proportion (molar ratio) betweenconstitutional units (1/m) in the structural formula) acquired by¹³C-NMR was 50/50.

(A2)-2: A polymer compound represented by Chemical Formula (A2-2). Thepolymer compound (A2-2) was obtained by radically polymerizing amonomer, from which a constitutional unit constituting the polymercompound was derived, using a predetermined molar ratio. Theweight-average molecular weight (Mw) of the polymer compound (A2-2) andthe molecular weight dispersity (Mw/Mn) in terms of standard polystyreneacquired by GPC measurement were respectively 7100 and 1.72. Thecopolymer compositional ratio (the proportion (molar ratio) betweenconstitutional units (1/m/n) in the structural formula) acquired by¹³C-NMR was 40/50/10.

(B1)-1: Acid generator formed of the following compound (B1-1)

(D0)-1 to (D0)-3: Acid diffusion control agents formed of compoundsrespectively represented by Chemical Formulae (D0-1) to (D0-3)

(D2)-1 to (D2)-3: Acid diffusion control agents formed of compoundsrespectively represented by Chemical Formulae (D2-1) to (D2-3)

(S)-1: A mixed solvent of propylene glycol monomethyl ether acetate andpropylene glycol monomethyl ether at a mass ratio of 60/40

<Formation (1) of Resist Pattern>

An 8-inch silicon substrate to which a hexamethyldisilazane (HMDS) hadbeen applied was coated with the resist composition of each exampleusing a spinner, and a prebake (PAB) treatment was performed thereon ona hot plate at a temperature of 110° C. for 60 seconds so that the hotplate was dried to form a resist film having a film thickness of 50 nm.

Next, drawing (exposing) was performed on the resist film at anaccelerating voltage of 100 kV such that the target size was set to aline width of 50 nm to 20 nm and 1:1 line and space pattern(hereinafter, referred to as an “LS pattern”) using an electron beamlithography device JEOL-JBX-9300FS (manufactured by JEOL Ltd.).Thereafter, a post exposure bake (PEB) treatment was performed thereonat 90° C. for 60 seconds.

Subsequently, alkali development was performed at 23° C. for 60 secondsusing a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueoussolution “NMD-3” (trade name, manufactured by TOKYO OHKA KOGYO CO.,LTD.).

Thereafter, water rinsing was performed for 15 seconds using pure water.

As the result, a 1:1 LS pattern with a line width of 50 nm to 20 nm wasformed.

[Evaluation of Optimum Exposure Amount (Eop)]

An optimum exposure amount Eop (μC/cm²) at which the LS pattern with atarget size was formed according to the method in the section of“formation of resist pattern” was acquired. The results are listed inTables 3 and 4 in the columns of “Eop (C/cm²)”.

[Evaluation of Line Width Roughness (LWR)]

Using the LS pattern formed in the section of the “formation of resistpattern”, the 3σ which is the scale that indicates the LWR was acquired.The results are listed in Tables 3 to 4 in the columns of “LWR (nm)”.

The “3σ” indicates three times (3σ) (unit: nm) the standard deviation(σ) acquired based on the result of measurement performed by measuring400 sites of line positions in the longitudinal direction of the lineusing a scanning electron microscope (trade name: S-9380, manufacturedby Hitachi High-Technologies Corporation, accelerating voltage of 800V).

In a case where the value of the 3σ is small, this indicates that theroughness of a line side wall is small and an LS pattern with a uniformwidth is obtained.

[Evaluation of Resolution]

An optimum exposure amount Eop (μC/cm²) at which the LS pattern with atarget size was formed according to the method in the section of“formation of resist pattern” was acquired. In addition, the minimumdimension of a pattern to be resolved without collapsing while theexposure amount from the optimum exposure amount Eop was increased toform an LS pattern was acquired using a scanning electron microscopeS-9380 (manufactured by Hitachi High-Technologies Corporation). Theresults are listed in Tables 3 and 4 in the columns of “resolution(nm)”.

TABLE 3 PAB PEB Eop LWR Resolution (° C.) (° C.) [μC/cm²] (nm) [nm]Example 1 110 90 90 4.2 30 Example 2 110 90 89 4.0 28 Example 3 110 9086 4.1 30 Example 4 110 90 92 4.3 32 Example 5 110 90 92 4.1 30 Example6 110 90 94 4.4 30 Example 7 110 90 98 4.3 32 Example 8 110 90 92 4.2 32Example 9 110 90 94 4.1 30

TABLE 4 PAB PEB Eop LWR Resolution (° C.) (° C.) [μC/cm²] (nm) [nm]Comparative 110 90 124 5.0 46 Example 1 Comparative 110 90 129 5.0 48Example 2 Comparative 110 90 118 5.1 50 Example 3 Comparative 110 90 1305.2 48 Example 4 Comparative Example 5 110 90 129 5.3 48

Based on the results in Tables 3 and 4, according to the resistcomposition of each example to which the present invention has beenapplied, it was confirmed that a resist pattern which has excellentsensitivity, reduced roughness, and excellent resolution in theformation of a resist pattern can be formed.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Additions,omissions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims.

What is claimed is:
 1. A resist composition which generates an acid upon exposure and whose solubility in a developing solution is changed due to an action of the acid, the resist composition comprising: a resin component (A1) whose solubility in a developing solution is changed due to the action of an acid; an acid generator component (B) that generates an acid upon exposure; and a compound (D0) formed of an anion moiety and a cation moiety, which is represented by Formula (d0), wherein the resin component (A1) has a constitutional unit (a0) obtained from a compound represented by Formula (a0-1), in which a polymerizable group at a W portion is converted into a main chain, and a constitutional unit (a1) containing an acid decomposable group whose polarity is increased due to the action of the acid:

wherein M^(m+) represents an m-valent organic cation, R^(d0) represents a substituent, p represents an integer of 0 to 3, and in a case where p represents 2 or 3, a plurality of substituents as R^(d0) may be the same as or different from one another, q represents an integer of 0 to 3, and n represents an integer of 2 or greater, where a relationship of “n+p≤(q×2)+5” is satisfied,

wherein W represents a polymerizable group-containing group, Wa^(x0) represents an (n_(ax0)+1)-valent aromatic hydrocarbon group which may have a substituent, and n_(ax0) represents an integer of 1 to
 3. 2. The resist composition according to claim 1, wherein the compound (D0) is a compound formed of an anion moiety and a cation moiety, which is represented by Formula (d0-1):

wherein R^(d1) represents an aryl group which may have a substituent, R^(d2) and R^(d3) each independently represent an aryl group which may have a substituent or R^(d2) and R^(d3) may be bonded to each other to form a ring with a sulfur atom in the formula, R^(d0) represents a substituent, p represents an integer of 0 to 3, and in a case where p represents 2 or 3, a plurality of substituents as R^(d0) may be the same as or different from one another, q represents an integer of 0 to 3, and n represents an integer of 2 or greater, where a relationship of “n+p≤(q×2)+5” is satisfied.
 3. A method of forming a resist pattern, comprising: forming a resist film on a support using the resist composition according to claim 1; exposing the resist film; and developing the exposed resist film to form a resist pattern.
 4. The method of forming a resist pattern according to claim 3, wherein the resist film is exposed to extreme ultraviolet rays (EUV) or electron beams (EB). 